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. The organization maintains a vast database of variable star observations, which is used by scientists worldwide. By collaborating with both amateur and professional astronomers, the AAVSO plays a crucial role in advancing our understanding of stellar behavior and the dynamics of the universe.