"Man on the Moon: The End of Day" is the debut studio album by American rapper Kid Cudi, released on September 15, 2009. The album features a blend of hip-hop, rock, and electronic music, showcasing Cudi's unique style and introspective lyrics. It includes popular tracks like "Day 'n' Nite" and "Pursuit of Happiness," which explore themes of loneliness, dreams, and self-discovery. The album received critical acclaim for its innovative sound and emotional depth, helping to establish Kid Cudi as a significant figure in the music industry. It also contributed to the rise of alternative hip-hop, influencing many artists in the genre.