iMac is a ranged all-in- one desktop computers made by Apple Inc. under the Macintosh line. It has been the prime part of Apple’s desktop proposal since its released in 1998, and has pass through 4 distinct forms. The original one, the iMac G3, was shaped and had a CRT monitor, enclosed by translucent plastic. The 2nd major upgrade, the iMac G4, had a hemispherical base design with a LCD monitor and all the main components. The Intel iMac and the iMac G5 placed all the hardware components behind the monitor, creating a short and thick unified design that angles up and down on a metal base. The last iMac have the same shape as the previous, but is a little more thinner and made from aluminum and black bordered glass for the case.

iMac received a lot of considerable critical attitudes, including express approval of Walt Mossemberg, an american journalist who works like the principal columnist for the Wall Street Journal and who named it the “Gold standard of desktop computers”. CNET said about the first 24 inches Core 2 Duo that it’s a “must-have desktop” and the Forbes Magazine about the original colored line that it is an “industry altering success”.

On the start of the 2009, in March, Apple upgraded iMacs with new Nvidia chipsets a new keyboard without numeric pad keys and a new Mini Display Port.

On October 20, 2009, Apple added to iMac two new LED backlit 16:9 widescreen at 21,5″ and 27″, instead of the old 20″ and 24″ which had a 16:10 aspect ratio. Also the hard drive and memory capacity increased and 2 new Core chips, i5 and i7 was added, starting a new era of iMac quad cores.

The dimensions of the display varied from generation to generation. So if the iMac G3 had a 15 inches CRT, the Aluminum iMac it is available in 4 types of LCD, of 20″, 21,5″, 24″ or 27″, despite the Intel Plastic iMac model that was available only in 3 variants of 17, 20 or 24 inches, also LCD.

The capacity of the hard drive varied also with every major upgrade. If at the start the iMac was available in 2 options of 4 and 60 gigabytes, now, the aluminium model can be bought with 250 GB or 2 Terabytes.

The Mac Operating system used, also have been upgraded year by year, now, the ultimate version been Mac OS X 10.6 .

In October, 2009, Apple Inc. released a  long expected refresh of iMac line. The 27″ model have a digital video input port for a better allowing of the system to hold as a screen for other devices. Video card  was changed into ATI and the processor have been significant upgraded to Core 2 Duo.  The high end model have also implemented Core i5 and Core i7 chip sets, allowing the new iMac to be named as quad core for the first time. The default RAM  has been increased and the memory slots have been doubled, the maximum memory capacity also was doubled to 16 GB.

Dan Frakes from MacWorld advises that if they will keep iMac occupying the mid-range of Apple Inc.’s product line, Apple have nothing else to offer to the users which want some ability to expand or upgrade their personal computers but can’t afford or just don’t need a Mac Pro.

A new upgrade to the iMac was a removable mobile PCI express Module (MXM) as an interconnect standard for graphic modules.

The prime model of iMac was the first released Macintosh that included an USB port, but being the only interface for peripheral built -in it. The unexpected success and popularity of this product helped the introduction of this interface among all the computer’s industry.

Via this USB port, hardware producers could make some products that are able and compatible to work with both PCs and iMacs. Before this, Macintosh users had to look for a certain hardware, like mice and keyboards, special oriented and made for Mac’s unique interface. Only two or three models of peripherals from specified manufacturers were made for this interfaces, and often was pretty expensive. Through the introduction of USB, the iMac users have been allowed to acquire a large collection of more cheaper devices and gadgets, like hubs, storage devices, scanners, keyboards, mice and USB flash drives. But as USB was pretty slower than a number of other type of ports available at that time like SCSI, iBooks and iMacs were pretty badly deprived in their efficiency until adequate replacements was released, such as Fire Wire or USB 2.