The iMac G4 was a computer

Computer

A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

 that was produced by Apple from the beginning of 2002 to mid 2004. It replaced the aging iMac G3

IMac G3

The iMac G3 was the first model of the iMac line of personal computers made by Apple Inc. , and the originator of the Legacy-free PC market category. Like the first Macs, the iMac G3 is an all-in-one personal computer, encompassing both the monitor and the system unit in a single enclosure...

. The computer had a new design compared to older Macs. It had a 15-inch LCD

Liquid crystal display

A liquid crystal display is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals . LCs do not emit light directly....

 which was mounted on an adjustable arm above a hemisphere containing a full-size, tray-loading optical drive and a sixteenth-generation CPU (the PPC 74xx-series

PowerPC G4

PowerPC G4 is a designation used by Apple Computer to describe a fourth generation of 32-bit PowerPC microprocessors. Apple has applied this name to various processor models from Freescale, a former part of Motorola....

). This LCD computer was known and sold as The New iMac, while existing egg-shaped iMac was renamed the "iMac G3" and continued to be sold for a few months.