Ergosterol is a sterol compound found primarily in the cell membranes of fungi, yeast, and some protozoa. It plays a crucial role in maintaining membrane fluidity and integrity, similar to how cholesterol functions in animal cells. Ergosterol is also a precursor for the synthesis of important molecules, including vitamin D2 when exposed to ultraviolet light. In addition to its biological functions, ergosterol is significant in medical and pharmaceutical contexts. It serves as a target for antifungal medications, such as amphotericin B and fluconazole, which disrupt ergosterol synthesis or function, ultimately leading to the death of fungal cells.