Alga is a generic term used to describe a diverse group of aquatic organisms that can be found in various ecosystems including oceans, rivers, lakes, and even in moist soil. These organisms can range in size, shape, and color, with some appearing as simple single-celled organisms while others form complex multicellular structures. Algae play a crucial role in the environment as they are primary producers, meaning they are able to convert sunlight into energy through photosynthesis. They also serve as a food source for many aquatic organisms and can contribute to the oxygen levels in the atmosphere. While some algae can be harmful and cause blooms that can be detrimental to ecosystems, others have proven to be valuable resources for food, fuel, and pharmaceuticals.