Chlorophyte algae (which means green algae) are a highly diverse group of algae that inhabit freshwater, marine, and terrestrial environments worldwide, although their greatest diversity is found in freshwater.

They are generally unicellular organisms or form simple colonies, although they occasionally become multicellular but with little cellular organization. They are distinguished from other groups of algae by ultrastructural characteristics, such as the type of cytoskeletal organization at the base of the flagella. They exhibit varied morphologies, but unicellular forms, which may or may not have flagella, colonial forms (some relatively complex), or filamentous forms are common. Their life cycles are highly varied.