OutKast's ATLiens, their second studio album, is a groundbreaking hip-hop record celebrated for its unique sound, lyrical depth, and innovative production. The album explores themes of urban life, existentialism, and even extraterrestrial existence, all while showcasing the duo's expanding musical palette. ATLiens is considered a masterpiece and a significant milestone in hip-hop history, contributing to the genre's evolution. 
The album spawned several hit singles, including "Elevators (Me & You)," "ATLiens," and "Jazzy Belle."