What is the significance of algae for humans?

Algae play an important role in human life. Both directly and through other systems. Plants are also the first link in aquatic food chains. Therefore, there are aquatic inhabitants that humans also eat. Algae also enrich water with oxygen through photosynthesis. Some seaweed is used by humans for cooking, some for industrial purposes. In food, textile, pharmaceutical, chemical, there is also a use for algae. But initially, it was thanks to algae that the atmosphere changed and provided life for further species on the planet.