Bits and Bytes
The following will go up in order of File Sizes from Bit to Terabyte.
A
bit is the basic unit of information in computing and digital communications. A bit can have only one of two values, and may therefore be physically implemented with a two-state device. The most common representation of these values are
0and1 or off and on. The term
bit is a contraction of
binary digit.
A
Nibble (often
nybble or even
nyble to match the vowels of
byte) is a four-bit aggregation,or half an octet. As a nibble contains 4 bits, there are sixteen possible values, so a nibble corresponds to a single hexadecimal digit.
A
byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit of memory in many computer architectures. The size of the byte has historically been hardware dependent and no definitive standards existed that mandated the size. The
de facto standard of eight bits is a convenient power of two permitting the values 0 through 255 for one byte. The popularity of major commercial computing architectures has aided in the ubiquitous acceptance of the 8-bit size.
The
kilobyte for 1000 bytes (symbol:
kB) or
Kilobyte (
kibibyte) for 1024 bytes (symbol:
KB or
KiB or informally
KBytes) are two definitions for multiples of the unit byte for digital information. The term
kilobyte and the symbol
KB have historically been used to refer to 1024 (2
10) bytes, in the fields of computer science and information technology.
The
megabyte (symbol
MB, sometimes abbreviated as
Mbyte) is a multiple of the unit byte for digital information storage or transmission with three different values depending on context:
1000000 bytes (10
6, see prefix mega-) generally for computer storage or transmission rates;
[ 1048576 bytes (2
20, or a mebibyte) generally for computer memory; and in rare cases
1000×1024 (
1024000) bytes.
The term "gigabyte" is commonly used to mean either 1000
3 bytes or 1024
3 bytes. This originated as compromise technical jargon for the byte multiples that needed to be expressed by the powers of 2 but lacked a convenient name. As 1024 (2
10) approximates 1000 (10
3), roughly corresponding SI multiples, it was used for binary multiples as well. In 1998 the International Electrotechnical Commission (IEC) proposed standards for binary prefixes and requiring the use of gigabyte to strictly denote 1000
3 bytes and gibibyte to denote 1024
3 bytes. By the end of 2007, the IEC Standard had been adopted by the IEEE, EU, and NIST.
The
terabyte is a multiple of the unit byte for digital information. The prefix
tera represents the fourth power of 1000, and means 10
12 in the International System of Units (SI), and therefore one terabyte is one trillion (short scale) bytes. The unit symbol for the terabyte is
TB.
1 TB =
1000000000000bytes =
1012bytes =
1000gigabytes. A related unit, the tebibyte (TiB), using a binary prefix, is the corresponding 4th power of 1024. One terabyte expressed using binary prefixes is about 0.910 tebibytes, or 931 gibibytes.
