In the beginning was the bit. A bit is 1 or 0

Bits were put together to make bytes

There are exactly eight bits in a byte, and 1 byte = one letter or punctuation mark

for example:

01101000 = h
and
01101000 01100101 01101100 01101100 01101111 = hello.

one thousand letters makes a kilobyte, or approximately 125 words.

one thousand kilobytes should make a megabyte, but in fact (because we are using base 8 - remember 8 bits in a byte?) - 1024 kilobytes make a megabyte.

a megabyte can hold as much text as a small paperback book.

a gigabyte is one thousand megabytes. A 2 hour film can be stored on 4-6 gb.

a terabyte is one thousand gigabytes, or 1,099,511,627,776 bytes

This is enough for almost everything, but some very large storage space is measured in petabytes, or thousands of terabytes.

Now let's jump to the top of the scale and look at a brontabyte

or a little bit more than 10,000,00,000,000,000,000,000,000,000 bytes. This is enough for you to store a 150 word letter to your mother, and another to her friend, and another to every person on the planet, with space left over for their pets.