Modem is short for Modulator-demodulator. What happens when you use a 56k modem is you send data that has been modulated so the phone lines understand it. When you receive data through a modem you are demodulating, and returning it into digital data. So basically what you have is a form of compression. The first modem was invented in the 60's for businesses, the time line of the evolution of modems are as follows
?300 bps - 1960s through 1983 or so
?1200 bps - Gained popularity in 1984 and 1985
?9600 bps - First appeared in late 1990 and early 1991
?19.2 kilobits per second (Kbps)
?56 Kbps - Became the standard in 1998
?ADSL, with theoretical maximum of up to 8 megabits per second (Mbps) - Gained popularity in 1999
The reason for the evolution In modems is due to the fact that people were starting to transfer more an more data.
Such as programs and since programs constantly grew in size due to the quality of the GUI (Graphical User Interface) and size of the files themselves modems had to grow in speed because it would take an unreasonable amount of time to transfer something. In the beginning people created bulletin boards that shared views on certain topics and the speed of the modem was 300bits per second this was okay because that was 30 characters typed on the keyboard a second and no one was that fast, but when programs began to transfer that's when they noticed how slow the modem actually was. Modems transfer and receive data in full-duplex which means that it sends and receives data at the same time modems that transfer only one way are called half-duplex. When modems evolved the creators of the modems had...