In terms of functionality and availability the Apple desktops that you are most likely to see on eBay or from the iMac family.

iMacs got their start in 1997 when Steve Job’s decided to rationalize Apple’s desktop offerings. The very first direct ancestor of the iMac was the Power Macintosh G3. It was not much different than other desktops in that it had a separate monitor, keyboard, and a tower box. Part of the structural change was the rollout of the of the G3 All-in-One, sold only to the educational market.The G3 refers to the fact that this is the third in the generation of PowerPC microprocessors from the PowerPC 750 family produced by IBM and Motorola.

It is important to note that many iMac G3’s are still in use in schools around the world.

iMac G3

Later on in 1998, Apple introduced the iMac G3. This model was brought in to appeal to the consumer market; and with its radical integrated design (see picture below), it was Apple’s most successful product launch.

This model continued to be produced up until January of 2002. Throughout its history the iMac G3 was continually upgraded. Initial upgrades included a slot loading optical drive, additional graphics capability, and the slot for an Airport card. Subsequent model upgrades included the addition of CD-ROM and DVD-ROM drives, and increased processing speed-eventually topping out at 700 MHz.

iMac G4

In January 2002, Apple introduced the iMac G4. The iMac G4 was a totally different design from its predecessor. Rather than being a fully integrated computer, it had a LCD monitor mounted on the CPU with a separated keyboard. As with the iMac G3 series, the iMac G4 experience continual upgrades. The most significant upgrades occurring in the size of the monitor.

Wedged in the timeline was the introduction in 2002 of the eMac. This is essentially a G4 powered Macintosh in the familiar egg shaped the iMac G3-this time with a 17 inch CRT. The “e” stands for education-but this became insignificant when it was released months later to the general public.

iMac G5

In the summer of 2005, the iMac G4 was replaced by the iMac G5 to mixed reviews. It is to be the last in the line of the iMac computers that used a PowerPC chip. The iMac G5 was a more powerful machine compared to the G4. Unlike the iMac G4, the iMac G5 had an integrated monitor and CPU with a detached keyboard. Upgrades to the iMac G5 included more power, more RAM Airport extreme wireless, Bluetooth, as well as other graphical and network upgrades.

By November 2005 when Walt Mossberg of the Wall Street Journal declared that the iMac G5 was “the gold standard of desktop PCs”, the iMac G5 featured remote control, the built-in US B. 2.0 iSight camera, and a sleeker, thinner design.

iMacs Today

In 2006 Apple introduced its current line of iMacs. The core duo, soon to be core 2 Duo, featured an Intel chip. These machines kept the design of the iMac G5 but were made sleeker with the use of a combination of plastics and metals. They’re processing speeds were 2-3 times faster than their predecessors.