Data consists of numbers, text, sounds, images, videos, etc. In order to define them in the real world, we are using numbers (0-9), letters (A-Z) and symbols (@,[,\, etc) or a combination thereof. For example:
2012 (number)
Wikiversity (letters)
3<5 (combination of numbers and symbols)
X=(Y*Z)+W-U (combination of alphabet and symbols)
N123 (combination of letters and numbers)
Computers, however, don't understand the definitions for numbers (0-9), letters (A-Z) and symbols (@,[,\, etc), so in order to process those pieces of information a unique code must be assigned to each of them. The unique code for numbers, letters, and symbols is a binary numeral.
In practical use, each "0" and "1" in binary number uses a Physical attribute that is electrical or magnetic. The smallest part of that Physical attribute is named "Bit", the existence of the Physical attribute is "1", and the absence of the Physical attribute is "0"; 8 bits grouped up are called 1 Byte (so 1 byte=8 bits).
The binary numeral system, or base-2 number system, represents numeric values using two symbols - 0 and 1.
Examples:
numerical value " 0 " is 0. The unique code for 0 is → 00000000
numerical value " 1 " is 1. The unique code for 1 is → 00000001
numerical value " 2 " is 10. The unique code for 2 is → 00000010
numerical value " 3 " is 11. The unique code for 3 is → 00000011
numerical value " 4 " is 100. The unique code for 4 is → 00000100
numerical value " 5 " is 101. The unique code for 5 is → 00000101
numerical value " 6 " is 110. The unique code for 6 is → 00000110
numerical value " 7 " is 111. The unique code for 7 is → 00000111
numerical value " 8 " is 1000. The unique code for 8 is → 00001000
numerical value " 9 " is 1001. The unique code for 9 is → 00001001