{{About|the block that detects block updates|the redstone mechanism|block update detector}}
{{Block
| image = Observer.png
| image2 = Observer (back).gif
| invimage = Observer
| transparent = Partial
| light = No
| tool = wooden pickaxe
| renewable = Yes
| stackable = Yes (64)
| flammable = No
| lavasusceptible = No
}}
An '''observer''' is a [[block]] that emits a quick [[Redstone Dust|redstone pulse]] from its back when the block or fluid directly in front of its "face" experiences a change.

== Obtaining ==
=== Breaking ===
An observer requires a [[pickaxe]] to be mined. When mined without a pickaxe, it drops nothing.
{{breaking row|Observer|Pickaxe|Wood|horizontal=1}}

=== Crafting ===
{{Crafting
  |A1=Cobblestone
  |B1=Cobblestone
  |C1=Cobblestone
  |A2=Redstone Dust
  |B2=Redstone Dust
  |C2=Nether Quartz
  |A3=Cobblestone
  |B3=Cobblestone
  |C3=Cobblestone
  |Output=Observer
  |type=Redstone
}}

== Usage ==
An observer is placed similarly to a [[piston]]. It observes the block that it is placed against. The texture of the detecting side is that of an observing face. As observers can detect the state of other observers, placing two adjacent observers, each watching the other, can make a fast and compact redstone clock. They send out a [[Mechanics/Redstone/Pulse circuit|pulse]].

=== Behavior ===
{{IN|java}}, an observer detects changes in its target's block states, or the breaking or placing of a block (i.e. changes in its block state, but ''not'' its block entity data). This means that changes like the age of crops can be detected because they are part of the block states.

{{IN|bedrock}}, an observer acts as a block update detector and detects anything that causes a block update.

The causes and propagation of block updates are different between ''Java Edition'' and Bedrock Edition. As a result, each can detect some kinds of changes that the other cannot. See the table below for a comparison.

When it detects something, the observer emits a [[Pulse circuit|redstone pulse]] of [[Redstone circuit#Power|strong power]] at level 15 for 2 [[game tick]]s (1 [[redstone tick]]). The pulse can power [[redstone dust]], a [[redstone comparator]], a [[redstone repeater]], or any [[Redstone components#Mechanism components|mechanism component]] located at its opposite end.

{{IN|java}}, the pulse is emitted with a delay of 1 redstone tick. In Bedrock Edition, it is supposed to be delayed by 1 tick as well but is actually delayed 2 redstone ticks due to {{bug|MCPE-15793}}, a bug causing redstone delays to be incorrect when components are activated by world changes (which, in the case of the observer in Bedrock Edition, is the only way it can be activated), as opposed to pure redstone components ticking. Its timing can also be incorrect due to {{bug|MCPE-73342}}.

It also counts as a block update when the observer itself is moved by a piston. When this happens, an observer emits a pulse after being pushed or pulled, but not beforehand. This enables them to be used in [[Tutorials/Flying machines|flying machines]].

Observers behave as both opaque and transparent blocks: they block light and allow mob spawning on top, but do not block opening chests below, do not cut off redstone wire, and cannot conduct redstone power.

Because observers in ''Java Edition'' detect changes in the block state, and ''not'' block updates, they can detect a wider range of phenomena than a [[Tutorials/Block update detector|block update detector]] (BUD) circuit in Bedrock ''Edition'' can detect (as some block state changes don't cause block updates). Observers in Bedrock Edition ''do'' detect block updates but not block state changes, and so they detect the exact same things that any other BUD would detect in that edition.

=== Limitations ===
{| class="sortable fandom-table wikitable collapsible collapsed"
! rowspan="2" | Change in block state
! colspan="2" | Detected in
|-
! {{el|be}}
! {{el|je}}
|-
| <div class="mw-collapsible mw-collapsed">{{BlockSprite|oak-planks}} A [[block]] or a [[fluid]] being placed or broken in any way; either directly by [[player]], [[enderman]], or [[ravager]] or through:
<div class="mw-collapsible-content" style="column-count:2">
* Placing/breaking two-block-tall/wide blocks
* [[Snow golem]] or [[snowfall]] creating [[snow]]
* Snow melting
* [[Dispenser]] placing [[carved pumpkin]], [[wither skull]], or [[shulker box]]
* Creating/removing [[fluid]] using player or dispenser
* Placing [[scaffolding]] on top/side of another scaffolding
* [[Entities]] that is on [[fire]] touching [[powder snow]], causing it to melt
* Block being broken by fluid, (sticky) [[piston]], [[explosion]], [[opacity]],<ref>For example, a [[button]] cling on a block, when break the block that a button are clinging, that button will break and cause block update which can be detect by observer.</ref>
* Inconsonant [[light level]]<ref>For example, a [[mushroom]] are on light level of 13, according to Minecraft Wiki, at level 13 and above, mushroom will uproot unless on [[mycelium]], [[podzol]] or [[nylium]]. When update the mushroom, that mushroom will break and cause block update which can be detect by observer.</ref><ref>Another example, a [[wheat]] block are on light level of 0, according to Minecraft Wiki, at level 0 and below, wheat block will uproot. When update the wheat, that wheat will break and cause block update which can be detect by observer.</ref>
* Flammable blocks getting burned up by [[fire]] or [[lava]]
* A [[falling block]] turn into a [[falling block]] entity and vice versa
* [[Cactus]] breaking by placing a [[solid block]] next to it
* [[Villager]] planting and destroying crops
* [[Zombie]] breaking [[door]]s
* [[Leaves]] decaying
* [[Chorus Plant (block)|Chorus plant]] break due to their invaild placement<ref>For example, place 2 chorus plants on top of an [[end stone]]. When place a chorus plant on the side of the bottom one, that "bottom" chorus plant will break and cause block update which can be detect by observer.</ref>
* Using up a [[damaged anvil]], causing the damaged anvil to [[break]]
* Eating all the [[cake]]
* [[Water]] touching a [[sponge]], causing the area near the sponge to be removed and create a block update to the water
* Place the block into the replaceable block, replace a block by left-click and right-click at the same time;
* A wither rose block being planted after wither kills a mob if the ground is [[grass block]], [[dirt]], [[coarse dirt]], [[moss block]], [[mud]], [[soul sand]], [[soul soil]]{{only|JE|short=1}} or [[netherrack]]
* Left-clicking the [[dragon egg]], causing it to [[teleport]] and create a block update at the starting teleporting point and the teleporting destination of the dragon egg
* [[Boat]] and [[boat with chest]] breaking a [[lily pad]]
* [[Turtle]] laying [[turtle egg]](s), trampling an <code>eggs=1</code> [[turtle egg]] or turtle egg(s) hatching into baby turtle(s)
* Damaging a [[silverfish]], causing a nearby [[infested block]] turn into silverfish and create a block update
* [[Frog]] laying [[frogspawn]] or frogspawn hatch into [[tadpole]]
* Thrown [[trident]] breaks [[pointed dripstone]]
* [[Sniffer egg]] hatch into [[snifflet]]
* The upper part of [[pitcher crop]] spawn when apply bone meal on the pitcher crop that have block state <code>age</code> is 2
</div></div>
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|waterlogged chest}} [[Water]] being inserted to or removed from a block that can be [[waterlogged]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|water}} {{BlockSprite|lava}} A [[water]] (or [[lava]], if <code>lavaSourceConversion</code> is set to <code>true</code>{{only|java|short=1}}) source block being created by having 2 water source blocks unite to each other.
| {{tc|yes}}
| {{tc|Yes}}
|-
| <div class="mw-collapsible mw-collapsed">{{BlockSprite|fire}} {{BlockSprite|soul fire}} [[Fire]] being ignited or extinguished in any way; either directly by player or through:
<div class="mw-collapsible-content" style="column-count:2">
* A dispenser
* Fire spreading to flammable blocks next to [[lava]] or fire
* [[Fireball]] from a dispenser, a [[ghast]] or a [[blaze]]
* [[Lightning]]
* A [[bed]] or a [[respawn anchor]] [[exploding]]
* Place an [[end crystal]] on [[bedrock]] or [[obsidian]] in [[the End]]
* Being extinguished by [[fluid]], [[splash water bottle]], [[lingering water bottle]] or naturally</div></div>
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|soul fire}} A [[fire]] is turn into a [[soul fire]] (but not vice versa).
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|cauldron}} {{BlockSprite|water cauldron}} {{BlockSprite|lava cauldron}} {{BlockSprite|powder snow cauldron}} [[Fluid]] or [[powder snow]] being placed in or removed from a [[cauldron]] or the level of the [[water]]/lava/powder snow cauldron changing in any way, for example using [[bucket]] (empty, water, [[lava]], powder snow), [[bottle]], [[water bottle]], [[rain]], [[snowfall]], [[pointed dripstone]], burning [[entity]] on water/powder snow cauldron.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| Block being replace by {{cmd|setblock}}, {{cmd|fill}} or {{cmd|clone}} commands.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{ItemSprite|debug stick}} Change [[block state]] of block using [[debug stick]].{{only|java}}
| {{tc|N/A}}
| {{tc|No}}
|-
| {{BlockSprite|nether portal}} A [[nether portal]] being created.
| {{tc|Yes}}
| {{tc|No}}<ref>{{bug|MC-107664}}</ref>
|-
| {{BlockSprite|nether portal}} A [[nether portal]] being destroyed.
| {{tc|No}}<ref>{{bug|MCPE-130935}}</ref>
| {{tc|Yes}}
|-
| {{BlockSprite|end portal}} An [[end portal]] being created.
| {{tc|No}}
| {{tc|No}}
|-
| {{BlockSprite|end portal}} An [[end portal]] being destroyed.
| {{tc|No}}
| {{tc|Yes}}
|-
| {{EntitySprite|iron golem}} {{EntitySprite|snow golem}} {{EntitySprite|wither}} The creation of an [[iron golem]], a [[snow golem]] or a [[wither]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|piston}} {{BlockSprite|sticky-piston}} A (sticky) [[piston]] (head) extending or retracting.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|piston}} {{BlockSprite|sticky-piston}} A block being pushed or pulled by a (sticky) [[piston]]; either directly or stuck to [[slime block]] or [[honey block]] moved by the piston.<ref>If an observer being pushed/pulled by a (sticky) piston, that observer also powered.{{info needed|Does this work on BE?}}</ref>
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|monster spawner}} A [[monster spawner]] block activating.
| {{tc|No}}
| {{tc|No}}
|-
| {{BlockSprite|monster spawner}} The mob spawn of a [[monster spawner]] being changed using a [[spawn egg]].
| {{tc|No}}
| {{tc|No}}
|-
| {{BlockSprite|chest}} {{BlockSprite|trapped-chest}} {{BlockSprite|ender-chest}} A [[chest]], a [[trapped chest]] or an [[ender chest]] opening or closing.
| {{tc|No}}
| {{tc|No}}
|-
| {{BlockSprite|shulker-box}} A [[shulker box]] opening or closing.
| {{tc|No}}
| {{tc|Yes}}
|-
| {{BlockSprite|barrel}} A [[barrel]] opening or closing.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|chest}} The [[inventory]] of a block that a [[comparator]] can measure as a container changing.
| {{tc|No}}
| {{tc|No}}
|-
| {{BlockSprite|anvil}} The crack stage of an [[anvil]] changing after use.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|snow}} A [[snow]] layer being added into snow by [[player]] or by [[snowfall]].<ref>{{IN|java}} the [[game rule]] <code>snowAccumulationHeight</code> must be larger than {{cd|1}}.</ref>
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|beacon}} A [[beacon]] activating or deactivating.
| {{tc|Yes}}
| {{tc|No}}
|-
| {{BlockSprite|command block}} A [[command block]] producing a success.
| {{tc|No}}
| {{tc|No}}
|-
| {{BlockSprite|command block}} The unconditional/conditional stage of a command block changing.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|command block}} The impulse/chain/repeat stage of a command block changing.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|cake}} {{BlockLink|id=candle-cake}} A piece of a [[cake]] or a [[cake with candle]]s changing.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|hopper}} A [[hopper]] being activated or deactivated. (Turning the hopper on/off)
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|farmland}} Dry [[farmland]] changing between its six dry-looking hydration stages.
| {{tc|No}}
| {{tc|Yes}}
|-
| {{BlockSprite|farmland-wet}} [[Farmland]] changing between dry and humid or vice versa.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|dispenser}} {{BlockSprite|dropper}} A [[dispenser]] or a [[dropper]] activating or deactivating.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|dispenser}} {{BlockSprite|dropper}} {{BlockSprite|piston}} {{BlockSprite|sticky-piston}} A [[dispenser]], [[dropper]], [[piston]] or [[sticky piston]] changing [[quasi-connectivity]] state.<ref>The change of quasi-connected state usually coincides with some other block state change for these mechanisms, such as activating to dispense an item, or the piston head extending/retracting. Therefore, this effect is only noticeable when a dropper or dispenser "deactivates" by ''losing'' its quasi-connected status when the redstone power source is turned off. To demonstrate, use a lever to power a redstone repeater that quasi-connects to a dropper. Monitor the dropper with an observer. Turn the lever on. The dropper will drop an item and the observer will trigger. Turn the lever off. The dropper will not do anything, but the observer will trigger again because it detects the dropper's change in quasi-connected state.</ref>{{only|java}}
| {{tc|No}}
| {{tc|Yes}}
|-
| {{BlockSprite|redstone-ore}} {{BlockSprite|deepslate redstone ore}} A (deepslate) [[redstone ore]] block activating or deactivating.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|grass-block}} {{BlockSprite|mycelium}} {{BlockSprite|nylium}} {{BlockSprite|warped nylium}} [[Grass block]] or [[mycelium]] turning to [[dirt]] or [[nylium]] to [[netherrack]] after being spread using [[bone meal]] or grass block or mycelium decaying to dirt or nylium into netherrack.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|dirt}} [[Coarse dirt]] or [[rooted dirt]] converting into [[dirt]] through the use of a [[hoe]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|farmland}} [[Grass block]], [[dirt]], or [[dirt path]] converting into [[farmland]] through the use of a [[hoe]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|dirt path}} [[Grass block]], [[podzol]], [[mycelium]], [[dirt]], [[coarse dirt]], or [[rooted dirt]] converting into [[dirt path]] through the use of a [[shovel]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|dirt}} [[Farmland]] or [[dirt path]] converting into dirt.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|concrete powder}} [[Concrete powder]] converting into [[concrete]] through contact with [[water]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|sea pickle}} A [[sea pickle]] being added into a sea pickle.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|pink petals}} A [[Pink Petals|pink petal]] being added into a [[Pink Petals|pink petal]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|turtle egg}} A [[turtle egg]] being added into a turtle egg.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|turtle egg}} A [[turtle egg]] being removed from a turtle egg by breaking or trampling.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|turtle egg}}{{BlockSprite|sniffer egg}} The <code>hatch</code> [[block state]] of a [[turtle egg]] and a [[sniffer egg]] changing.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|infested stone}} A [[stone]], [[cobblestone]], [[deepslate]] or any [[stone brick]] variant block being turned into an [[infested block]] by [[silverfish]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|double smooth stone slab}} A double [[slab]] being created by adding a [[slab]] into another slab.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|ice}} [[Ice]] melting into [[water]] or water freezing into ice
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|frosted ice}} Water freezing into [[frosted ice]] through the use of [[Frost Walker]] or frosted ice melting into water
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|carved pumpkin}} Turn [[pumpkin]] into [[carved pumpkin]] using [[shears]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|stripped logs}} {{BlockSprite|stripped stems}} {{BlockSprite|block of stripped bamboo}} Turn [[log]]s/[[wood]]s/[[stem]]s/[[hyphae]]/[[block of bamboo]] into [[stripped log]]s/woods/stems/hyphae/[[block of stripped bamboo]] using [[axe]]s.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|saplings}} {{BlockSprite|bamboo}} The stage of a [[sapling]] or [[bamboo]] changing.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|mangrove propagule}} {{BlockSprite|bamboo}} {{BlockSprite|wheat}} {{BlockSprite|carrots}} {{BlockSprite|potatoes}} {{BlockSprite|beetroots}} {{BlockSprite|melon stem}} {{BlockSprite|pumpkin stem}} {{BlockSprite|nether wart}} {{BlockSprite|cocoa}} {{BlockSprite|sweet berry bush}} {{BlockSprite|chorus flower}} {{BlockSprite|cactus}} {{BlockSprite|sugar cane}} {{BlockSprite|kelp}} {{BlockSprite|weeping vines}} {{BlockSprite|twisting vines}} {{BlockSprite|cave vines}} {{BlockSprite|fire}} {{BlockSprite|frosted ice}} {{BlockSprite|torchflower crop}} {{BlockSprite|pitcher crop}} The age of [[mangrove propagule]]s, [[bamboo]], [[wheat]], [[carrot]]s, [[potato]]es, [[beetroots]], [[melon stem]], [[pumpkin stem]], [[nether wart]], [[cocoa]], [[sweet berry bush]], [[chorus flower]], [[cactus]], [[sugar cane]], [[kelp]], [[weeping vines]], [[twisting vines]], [[cave vines]], [[fire]], [[frosted ice]], [[torchflower crop]], or [[pitcher crop]] changing.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|torchflower}} A [[torchflower crop]] turning into a [[torchflower]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|water}} {{BlockSprite|lava}} [[Fluid]] flowing into the empty space to or draining from a block.<ref>When the fluid source block is removed, all of the fluid flowing from the source will also be removed and cause a block update.</ref>
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|water}} {{BlockSprite|lava}} {{BlockSprite|light}} {{BlockSprite|composter}} [[Fluid]], [[light block]], or [[composter]] level changing.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|stone}} (Flowing) [[water]] turning into [[stone]] through contact with [[lava]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|cobblestone}} Flowing lava turning into [[cobblestone]] through contact with water.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|obsidian}} Lava turning into [[obsidian]] through contact with water.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|basalt}} (Flowing) lava turning into [[basalt]] through contact with [[soul soil]] and [[blue ice]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|bubble column}} Water turning into [[bubble column]] or vice versa.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|bubble column}} Upward bubble column turning into whirlpool bubble column or vice versa.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|end portal frame}} An [[eye of ender]] being inserted into an [[end portal frame]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|red bed}} [[Player]] or [[villager]] sleeping/waking up in a [[bed]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|grass-block}} {{BlockSprite|mycelium}} {{BlockSprite|podzol}} A [[grass block]], a [[mycelium]] or a [[podzol]] block becoming snowy or not snowy.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|oak sign}} {{BlockSprite|oak hanging sign}} Text in a [[sign]] or a [[hanging sign]] being edited.
| {{tc|Yes}}
| {{tc|No}}
|-
| {{BlockSprite|oak sign}} {{BlockSprite|oak hanging sign}} A dye or glow being applied to a sign or a hanging sign or removed from it.
| {{tc|Yes}}
| {{tc|No}}
|-
| {{BlockSprite|oak sign}} {{BlockSprite|oak hanging sign}} Waxing a [[sign]] or a [[hanging sign]] using a [[honeycomb]].
| {{tc|Yes}}
| {{tc|No}}
|-
| {{BlockSprite|structure block}} {{BlockSprite|redstone-comparator}} The mode of a [[structure block]] or a [[comparator]] changing.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|grass-block}} {{BlockSprite|grass}} {{BlockSprite|fern}} A [[grass block]], [[grass]]{{only|BE|short=1}} or [[fern]]{{only|BE|short=1}} being grazed by a [[sheep]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|carrots}} A [[carrot]] crop being eaten by a [[rabbit]].
| {{tc|N/A}}<ref>{{IN|bedrock}}, rabbits do not eat carrot crops; see {{bug|MCPE-113321}} and {{bug|MCPE-131980}}.</ref>
| {{tc|Yes}}
|-
| {{BlockSprite|stone button}} A [[button]] being pressed or returning to inactive state.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|stone pressure plate}} {{BlockSprite|detector rail}} A [[pressure plate]] or the [[detector rail]] activating or returning to inactive state.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|weighted pressure plates}} {{BlockSprite|redstone wire}} {{BlockSprite|daylight detector}} {{BlockSprite|target}} The power of a [[weighted pressure plate]], [[redstone wire]], [[daylight detector]] or [[target]] changing.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|lever}} A [[lever]] being flicked.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|redstone lamp}} {{BlockSprite|redstone torch}} A [[redstone lamp]] or a [[redstone torch]] lighting up or turning off.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|daylight detector}} The mode of [[daylight detector]] being changed.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|TNT}} A [[TNT]] igniting.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|brain coral block}} {{BlockSprite|brain coral}} {{BlockSprite|brain coral fan}} [[Coral]]/[[coral block]]/[[coral fan]] converting into [[dead coral]]/[[dead coral block|coral block]]/[[dead coral fan|coral fan]].
| {{tc|Yes}}<ref>{{IN|bedrock}}, the death of a coral fan cannot happen under normal circumstances &mdash; it happens ''the very next tick after the coral fan is placed'', so the observer will already be reading the placement or water removal update, and coral fans placed using commands are waterlogged &mdash; but if lag is used to make the unwaterlogging and death events happen separately, the observer will detect both. For coral, the death also happens too fast for the observer to detect it separate from the placement or water removal, but a non-waterlogged coral can be placed using commands. Coral blocks take multiple seconds to die, and removing water next to the coral block does not activate the observer anyway, so they can be detected under normal circumstances.</ref>
| {{tc|Yes}}
|-
| {{BlockSprite|sponge}} A [[sponge]] turning into a [[wet sponge]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|wet sponge}} A [[wet sponge]] drying into a [[sponge]] in [[the Nether]].<ref>This event cannot normally happen, but if [[commands]] are used to place a wet sponge in the nether, the sponge will dry when it recieves a random tick.{{only|bedrock}} {{IN|java}}, sponges in the Nether always stay wet.</ref>
| {{tc|Yes}}
| {{tc|N/A}}
|-
| {{BlockSprite|oak-door}} A [[door]] being opened or closed by a [[player]], a [[villager]], a [[piglin]], a [[piglin brute]], a [[vindicator]]{{only|JE|short=1}}, a [[wandering trader]]{{only|BE|short=1}} or [[redstone]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|oak-trapdoor}} A [[trapdoor]] being opened or closed by a [[player]] or [[redstone]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|oak-fence-gate}} A [[fence gate]] being opened or closed by a [[player]] or [[redstone]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|oak-fence-gate}} The <code>in_wall</code> [[block state]] of a [[fence gate]] changing.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|furnace}} {{BlockSprite|blast furnace}} {{BlockSprite|smoker}} A [[furnace]], a [[blast furnace]] or a [[smoker]] lighting up or turning off.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|leaves}} {{BlockSprite|scaffolding}} The distance of [[leaves]] or a [[scaffolding]] changing.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|scaffolding}} The <code>bottom</code> [[block state]] of a [[scaffolding]] changing.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|brewing-stand}} A [[potion]] being moved in or out of a [[brewing stand]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|lectern}} [[Book and quill]] or [[written book]] being moved in or out of a [[lectern]].
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|note-block}} The note of a [[note block]] being changed.
| {{tc|No}}
| {{tc|Yes}}
|-
| {{BlockSprite|note-block}} A [[note block]] being left-clicked in [[Survival]] mode.
| {{tc|No}}
| {{tc|No}}
|-
| {{BlockSprite|note-block}} The <code>instrument</code> [[block state]] of a [[note block]] changing.
| {{tc|No}}
| {{tc|Yes}}
|-
| {{BlockSprite|jukebox}} A [[music disc]] being inserted to or removed from a [[jukebox]] by [[player]], [[hopper]], or [[minecart with hopper]].
| {{tc|No}}
| {{tc|Yes}}
|-
| {{BlockSprite|redstone-repeater}} A [[redstone repeater]] locking or unlocking.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|redstone-repeater}} The delay of a [[redstone repeater]] being changed.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|redstone-repeater}} {{BlockSprite|redstone-comparator}} {{BlockSprite|observer}} {{BlockSprite|note block}} {{BlockSprite|lectern}} {{BlockSprite|lightning rod}} {{BlockSprite|activator rail}} {{BlockSprite|powered rail}} {{BlockSprite|sculk sensor}} {{BlockSprite|calibrated sculk sensor}} {{BlockSprite|tripwire}} {{BlockSprite|tripwire hook}} A [[redstone repeater]], a [[redstone comparator]], an observer, a [[note block]], a [[lectern]], a [[lightning rod]], an [[activator rail]], a [[powered rail]], a [[sculk sensor]]<ref group="n" name="Sensor">When deactivated, the sculk sensor's and the calibrated sculk sensor's "sculk_sensor_phase" block stage is converted from "active"->"cooldown"->"inactive". However, this happens so fast that observer can't detect it, so that isn't counted.</ref>, a [[calibrated sculk sensor]]<ref group="n" name="Sensor"/>, a [[tripwire]], or a [[tripwire hook]] activating or deactivating.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|tripwire}} {{BlockSprite|tripwire hook}} A [[tripwire]] or a [[tripwire hook]] attaching or detaching.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|tripwire}} The <code>disarmed</code>{{only|java|short=1}} or <code>disarmed_bit</code>{{only|bedrock|short=1}} [[block state]] of a [[tripwire]] changing.<ref>The <code>disarmed</code>{{only|java|short=1}} or <code>disarmed_bit</code>{{only|bedrock|short=1}} block state cannot change without also detaching the tripwire, so this event cannot happen in isolation.</ref>
| {{tc|N/A}}
| {{tc|N/A}}
|-
| {{BlockSprite|sculk shrieker}} [[Sculk shrieker]] starting shrieking.
| {{tc|No}}<ref>{{IN|bedrock}}, observers detect when a sculk shrieker stops shrieking, but not when it starts shrieking.</ref>
| {{tc|Yes}}
|-
| {{BlockSprite|sculk shrieker}} [[Sculk shrieker]] stopping shrieking.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|sculk catalyst}} [[Sculk catalyst]] blooming or unblooming.
| {{tc|Yes}}
| {{tc|Yes}}
|-
| {{BlockSprite|dragon-head}} {{BlockSprite|piglin-head}} A [[dragon head]] or a piglin head activating or deactivating.
| {{tc|Yes}}
| {{tc|No}}
|-
| {{BlockSprite|conduit}} A [[conduit]] activating or deactivating.<ref>Since condu</ref>
| {{tc|N/A}}
| {{tc|N/A}}
|-
| {{ItemSprite|item-frame}} An [[item frame]] being placed or an item being added to, rotated in or removed from an item frame.
| {{tc|Yes}}
| {{tc|No}}
|-
| {{BlockSprite|end-gateway}} Something being teleported by an [[end gateway