O is the debut studio album by American R&B singer Omarion, released on February 22, 2005 via Epic Records and Sony Urban Music. Despite featuring explicit language, the album doesn't have a Parental Advisory label on the cover. It features three singles: the title track, "Touch" and "I'm Tryna." The album entered at number one on the Billboard 200, and has sold more than 750,000 copies in the United States as of November 2008. O went on to be certified Gold by the Recording Industry Association of America (RIAA) and was nominated for a Grammy Award for Best Contemporary R&B Album at the 48th Grammy Awards.

The album debuted at number one on the US Billboard 200 chart, selling 182,000 copies in its first week of release. In its second week, the album dropped to number eight on the chart, selling an additional 77,000 copies. In its third week, the album fell to number 12 on the chart, selling 45,030 more copies. On March 31, 2005, the album was certified gold by the Recording Industry Association of America (RIAA) for sales of over 500,000 copies in the United States. As of April 2012, the album has sold 765,000 copies in the United States.