The iMac is an "all-in-one" desktop Macintosh computer designed and built by Apple Inc. It has been a large part of Apple's consumer desktop offerings since its introduction in 1998, and has evolved through three distinct forms. In its original form, the G3, the iMac was egg-shaped with a CRT monitor, mainly enclosed by colored, translucent plastic. The second major revision, the G4, moved to a design of a hemispherical base containing all the main components and an LCD monitor on a freely-moving arm attached to the top of the base. The iMac G5 and the Intel iMac placed all the components immediately behind the monitor, creating a slim design which tilts only up and down on a simple metal base. The current iMac shares the same form as the previous models, but is now thinner and uses aluminum and glass for its case. (Also has a black and silver finish)

The machine enjoys a relatively high profile in popular culture due to its distinctive aesthetics and Apple's successful marketing. The iMac and other Macintosh computers can also be seen in various movies, commercials, and TV shows (both live action and animated).

The iMac has also received considerable critical acclaim, including praise from technology columnist Walt Mossberg as the “Gold Standard of desktop computing"; Forbes Magazine described the original candy-colored line of iMac computers as being an “industry-altering success”. The original 24" Core 2 Duo iMac received CNET's “Must-have desktop” in their 2006 Top 10 Holiday Gift Picks.