Chlorophyll (also chlorophyl) is any of several related green pigments found in the mesosomes of cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words χλωρός, khloros ("pale green") and φύλλον, phyllon ("leaf"). Chlorophyll is essential in photosynthesis, allowing plants to absorb energy from light.

Chlorophyll is a chemical in the chloroplasts of plants. It allows plants to absorb and use light. Energy from the light is used in photosynthesis to make glucose. This contains lots of stored energy which the plant needs to release. It does this through respiration. This energy is then used when the plant grows or repairs damage.