A Byte = one alphanumeric character i.e., – “a”

A bit (binary digit) is the smallest possible unit of information on a PC. A single bit can hold only one of two values: 0 or 1.

A byte (short for “binary term”) is capable of storing a single character. On PCs – a byte is equal to 8 bits.

A kilobyte (KB) is 1,024 bytes.

A megabyte (MB) is 1,048,576 bytes, or 1024 kilobytes

A gigabyte (GB) is 1,073,741,824 bytes, or 1024 megabytes.

A terrabyte (TB) is 1,099,511,627,776 bytes, or 1024 gigabytes

The following is from: Uplink.UK

This list is a collection of estimates of the quantities of data contained by the various media:

Bits

1 bit: A binary decision

Bytes (8 Bits)

1 byte: A single character

10 bytes: A single word

100 bytes: A sentence

Kilobyte (1024 Bytes)

1 Kilobyte: A page of text

10 Kilobytes: The size of this web page

100 Kilobytes: A compressed computer image OR a long essay

Megabyte (1024 Kilobyte)

1 Megabyte: A small novel OR A 3.5 inch floppy disk

2 Megabytes: A high resolution photograph

5 Megabytes: The complete works of Shakespeare

10 Megabytes: A minute of high-fidelity sound

100 Megabytes: 1 meter of shelved books

500 Megabytes: A CD-ROM

Gigabyte (1024 Megabyte)

1 Gigabyte: A symphony in high-fidelity sound OR A movie at TV quality

2 Gigabytes: 20 meters of shelved books

10 Gigabytes: A good collection of the works of Beethoven

20 Gigabytes: A VHS tape used for digital data

50 Gigabytes: A floor of books

100 Gigabytes: A floor of academic journals

Terabyte (1024 Gigabyte)

1 Terabyte: 50000 trees made into paper and printed

2 Terabytes: An academic research library

10 Terabytes: The printed collection of the US Library of Congress

100 Terabytes: The entire internet

Petabyte (1024 Terabyte)

1 Petabyte: 3 years of EOS data

10 Petabytes: All US academic research libraries

100 Petabytes: All printed material

Exabyte (1024 Petabyte)

1 Exabytes: All words ever spoken by human beings.

Zettabyte (1024 Exabyte)

Yottabyte (1024 Zettabyte)

1 Yottabyte: Everything that there is