The American Association of Variable Star Observers (AAVSO) is a non-profit organization dedicated to the study of variable stars. Founded in 1911, it encourages amateur and professional astronomers to observe and report changes in brightness of these stars. The AAVSO provides resources, training, and a platform for data collection, contributing to astronomical research. Members of the AAVSO participate in various projects, including monitoring supernovae, eclipsing binaries, and novae. The organization also collaborates with institutions and researchers, making its data available for scientific studies. Through its efforts, the AAVSO plays a vital role in advancing our understanding of the universe.