You need a modem to communicate to the internet world. A modem modulates the digital signals produced by your PC - turning them into analog ones for the phone lines. Then demodulates the incoming analog signals to digital for your PC.

The speed of a modem is measured in kilobits per second while your file sizes are measured in kilobytes and megabytes.

Now there are :

8 bits in a byte
1000 bits in a kilobit
1000 kilobits in a megabit
1024 bytes in a kilobyte
1024 kilobytes in a megabyte

bps -	bits per second			Mbits -	megabits
Kbps -	kilobits per second			Mbps -	megabits per second
K -	kilobyte			Mb -	megabyte
K/s -	kilobytes per second			Mb/s -	megabytes per second

Now with that out of the way , lets look at some modems. You can get a 14.4Kbps or 33.6Kbps but when looking for a modem , you are looking for speed.The fastest modems currently for home users is the 56K . The 56K promise a download speed of up to 56Kbps , but in the real world with line noise and signal quality, you can expect a download speed of up to 40-44Kbps and an upload speed of up to 33.6Kbps . Currently there are two formats of the 56K modem. It's the X2 format and the K56 Flex format. Both the formats can deliver the same performance. They are based on the same technology, but they are incompatible(cant understand each other). So be sure to choose a 56K format that matches the format supported by your service provider .Then again , just ask your service provider if they support V.90 .

V.90.
Different manufacturers have got together with the International Telecommunications Union(ITU) to produce a standard protocol for 56K technology.The V.90 standard will allow the X2 and Flex formats to speak to each other . This means that you will be able to buy a 56K modem without fearing for its compatibility.Some 56K modems produced before the standard was agreed, can be upgraded.