This document discusses algae, including their diversity, taxonomy, morphology, and impacts. It covers the major divisions of algae, including their distinguishing characteristics like photosynthetic pigments. Examples are provided of different algal forms ranging from unicellular to multicellular. Both beneficial roles of algae like food and industrial uses, as well as detrimental impacts like harmful algal blooms and shellfish poisoning are summarized. Specific examples are described to illustrate red tides, algal blooms, and cases of bird deaths potentially linked to algal toxins.