Photosynthesis is the process by which green plants, algae, and some bacteria turn sunlight into energy. It's crucial because it provides food and oxygen for life on Earth. Here’s a simple breakdown of how it works:

1. **Light Absorption**: Plants have a green pigment called chlorophyll found in their leaves. Chlorophyll absorbs sunlight, primarily using the blue and red parts of the light spectrum.

2. **Water and Carbon Dioxide Intake**: Plants get water from the soil through their roots and carbon dioxide from the air through tiny holes in their leaves called stomata.

3. **Chemical Reactions**: Inside the leaves, the sunlight, water, and carbon dioxide go through chemical reactions. These reactions happen in the chloroplasts, where chlorophyll is located. 

4. **Production of Glucose and Oxygen**: The energy from the sunlight is used to convert water and carbon dioxide into glucose (a type of sugar) and oxygen. Glucose serves as food for the plant, giving it energy to grow. Oxygen is released into the air, which we and other organisms need to breathe.

5. **Equation**: The process of photosynthesis can be represented by the equation: 
   \[
   6CO_2 + 6H_2O + \text{light energy} \rightarrow C_6H_{12}O_6 + 6O_2
   \]
   This means that six molecules of carbon dioxide and six molecules of water, using light energy, are converted into one molecule of glucose and six molecules of oxygen.

Overall, photosynthesis allows plants to create their own food and provides oxygen, sustaining life on Earth.