Bit

A bit is a binary digit with a value of either 0 or 1. For example, the number 10010111 is 8 bits long, or in most cases, one modern PC byte (8 bits = 1 byte). Binary digits are a basic unit of information storage and communication in digital computing. Larger bit units that are commonly used in computer systems include: kilobytes (kB), megabytes (MB), gigabytes (GB), terabytes (TB), and petabytes (PB).

Examples of the number of bits used in typical digital files:

Text file (such as Word or Excel): 32-70kB for around 1-2 pages
PDF document: 30kB for 1 page of text only
Uncompressed feature 5.1 audio (WAV): 12.2GB for 120 minutes of 24-bit 96kHz audio
Uncompressed feature mono audio (WAV): 2.0GB for 120 minutes of 24-bit 96kHz audio
Quicktime video feature (no audio embedded): 12.4GB for106 minutes @ 480i
Dolby® AC-3 compressed audio 5.1 feature: 363MB for 117 minutes
Typical internal hard disk drive: 500GB or 1TB
USB flash memory stick: 8GB
LTO-3 tape: 400GB uncompressed

This article is licensed under the GNU Free Documentation License found at http://www.gnu.org/copyleft/fdl.html. It uses material from the Wikipedia article at http://en.wikipedia.org/wiki/Binary_digit.