The Intel-based iMac is a family of Macintosh desktop computers designed, manufactured and sold by Apple Inc. since 2006. In the current product line, the iMac sits below the performance range iMac Pro.
Pre-2009 iMac models featured either a white polycarbonate enclosure or an aluminium enclosure. The October 2009 iMac model featured a unibody aluminum enclosure, a version of which can still be seen on the current model. The current iMacs released since October 2012 also feature a much thinner display, with the edge measuring just 5 mm.
Source: Wikipedia, "IMac (Intel-based)", available under the CC-BY-SA License.