If you connect to the Net through a modem and standard phone line, there have probably been times when you've dozed off waiting for a page to download into your browser window. Or torn your hair out with frustration because you were in a hurry. This congestion happens because each link whether it is a land-based cable, satellite or radio wave is only capable of transporting a certain amount of data per second. That capacity is called bandwidth.
All data is broken down into units called bits.
The bandwidth capacity of a telecommunications link is measured in bits per second. If more than 128kb arrives at the link at the same time, it will take more than one second to transport it between the two points. A good example is how Internet traffic varies depending on the time of day. Let's say you log on to the Net via your ISP at 2am. The link will be more efficient and surfing speed should be acceptable.