The iMac is a computer invented by Steve Jobs and the successor of the Macintosh. It was created in 1998
when Steve decided that he had gone to long without releasing a new version of the Mac to steal money from people. The iMac was made to combat this, and Steve Jobs loaded his pockets with even more cash.
The iMac is designed to function exactly like the Mac. The only difference is that having the iMac makes you popular, while having the old Mac makes you a loser. Steve Jobs intentionally put this thought into stupid people's minds so they would waste more money on him.
When Steve Jobs died, the iMac received an "upgrade" because it said so in Steve's will. By upgrade, I mean that every time you bought the iMac, it exploded. This was not intentional, simply the result of idiots having no idea what to do now that they didn't have good ole' Stevie looking over their shoulders 24/7. However, Tim Cook realized how stupid it was to follow Steve's will all the time when he gained the password to the secret iVault, so he made another "upgrade" that made it so that it didn't explode anymore. Also, good ole' Timmy doesn't look over your shoulders 24/7, so he can spend more time a) making products that are actually good for a change and b) hanging out with his wife and kids. On the other hand, iMacs are made of solid gold. Who cares if they cost 42 million dollars? GOLD! Although the retail ones only costs a small Un$4999.