The first computer, in it's most general form was first designed and used by the ancient Egyptians. The Abacus, even though unable to perform complex calculations, it was a machine that helped people compute mathematical operations, hence why we call it a computer.
The computer has gone through many revisions through history, ranging from the first computers, that were mechanical, to modern computer that are electronic.There have even been computer that were made to run on water! These computers were very basic and you needed to be able to understand and convert the binary system to it's decimal equivalent to use them.
More modern computers, on the other hand are run electronically. They run on binary, the pulse of electricity, on or off, and store the the information as a series of switches. The first electrical computers were the size of a large room, and because of their undependable nature, they had to be in a precisely climate-controlled room. They only preformed simple mathematical calculations and sorting. Their basic form of input was a punch-card. And they had to print the results to paper. As more and more companies invested money into the large machines, there was more stress on the manufacturers to decrease the size of the machines and increse their usability, performance and reliability.
In 1971 a small company called Intel debuted the first microprocessor called the 4004. A while later it introduced the 8008 and then the 8080. These processors were the foundation for all personal computers today. Microprocessors have branched off since then and have become specailized for their particular field.
In 1981 IBM released it's first Personal Computer, based on the Intel system structure. This brought the computer age into people's homes and on their office desks.
In 1984 Apple Computer Company released it's first version of the Macintosh. This was the first GUI, or Graphical User Interface. This made computers easier to understand and interface with. Microsoft, the company that had been writing DOS for the IBM machines, counteracts this is Windows, version 1.0 in 1985. Although, not the first GUI, Microsoft's Windows eventually overpowered the market, because of it's more advanced flexibility, power and customization features. Currently approximately 90% of new computer sales are IBM or compatible machines.
Well, that's it for the history of computers, now that you know the basics of where we've been we can focus on what we're doing now.