Photosynthesis is the process by which plants, algae, and some bacteria convert sunlight, water, and carbon dioxide into glucose (a type of sugar) and oxygen. Here's a simplified, step-by-step explanation:

1. **Inputs**: Plants require three main ingredients for photosynthesis:
   - **Sunlight**: Provides the energy needed for the process.
   - **Water**: Absorbed by roots and transported to the leaves.
   - **Carbon Dioxide**: Taken in from the air around the plant.

2. **Location**: Photosynthesis occurs in the chloroplasts of plant leaves. The green pigment chlorophyll in chloroplasts captures sunlight.

3. **Process**:
   - **Light-dependent Reactions**: In the thylakoid membranes, sunlight is absorbed and used to split water into oxygen, hydrogen ions, and electrons. This produces ATP and NADPH, energy-rich molecules.
   - **Calvin Cycle (Carbon Fixation)**: In the stroma, CO2 is fixed using ATP and NADPH to produce glucose.

4. **Outputs**: The process results in the creation of glucose, which plants use for energy and growth, and oxygen, which is released into the atmosphere.

5. **Importance**: Photosynthesis is vital as it provides oxygen for breathing and forms the base of the food chain, converting sunlight into chemical energy that sustains ecosystems.

In summary, photosynthesis is essential for life, enabling plants to create energy from sunlight, water, and CO2, while producing oxygen as a byproduct.