The iMac is a esktop 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 gum drop or 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 brushed aluminum and black-bordered glass for its case.