What are algae classified as?

Algae are classified as primitive and simple unicellular plants because they primarily consist of photosynthetic organisms that can vary in complexity. While some algae can form multicellular structures, such as seaweeds, most include unicellular forms like phytoplankton. These organisms are fundamental to aquatic ecosystems, serving as primary producers that convert sunlight into energy through photosynthesis. Their classification reflects their simpler structure compared to complex multicellular organisms such as flowering plants or animals, which have specialized tissues and organs. This classification also emphasizes their evolutionary history, as algae are considered to have originated early in the timeline of life on Earth.