LANs and WANs have
always had one thing in common, though, and that is the use of the
term bandwidth to describe their capabilities. This term is
essential for understanding networks but can be confusing at first, so
let's take a detailed look at this concept before we get too far into
networking.
Bandwidth is the measure of how much information can flow from one
place to another in a given amount of time. There are two common uses
of the word bandwidth: one deals with analog signals, and the other
with digital signals. You will work with digital bandwidth, called
simply bandwidth for the remainder of the text.
You have already learned that the term for the most basic unit of information is the bit. You also know that the basic unit of time is the second. So if we are trying to describe the
AMOUNT of information flow in a SPECIFIC period of time, we could use the units "bits per second" to describe this flow.
Bits per second is a unit of bandwidth. Of course, if
communication happened at this rate, 1 bit per 1 second, it would be
very slow. Imagine trying to send the ASCII code for your name and
address – it would take minutes! Fortunately, much faster
communications are now possible. The chart summarizes the various
units of bandwidth.