A "bit" is the smallest unit of measurement that a 
computer knows of. Bits have only two possible 
states -- they can be either "on" (1) or "off" (0). So:
  
  bit = 1 or 0

Because bits are so small, they're often grouped 
together into collections of 8, called a "byte". In other words:

 byte = 8 bits

Even larger collections of bits can be assembled, 
however. A kilobit (Kb) equals 1,024 bits while a 
kilobyte (KB) equals 1024 bytes:

  kilobit (Kb) = 1024 bits
  kilobyte (KB, or simply K)= 1024 bytes

Moral of the story? The more bits you have, the more 
information you have. In turn, the more space it takes 
to store that information on your computer or transmit 
it (download or upload) over the Internet or Web.

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