A bit (short for binary digit) is the smallest unit of data in a computer. A bit has a single binary value, either 0 or 1. Although computers usually provide instructions that can test and manipulate bits, they generally are designed to store data and execute instructions in bit multiples called bytes. In most computer systems, there are eight bits in a byte. The value of a bit is usually stored as either above or below a designated level of electrical charge in a single capacitor within a memory device.
Half a byte (four bits) is called a nibble. In some systems, the term octet is used for an eight-bit unit instead of byte. In many systems, four eight-bit bytes or octets form a 32-bit word. In such systems, instruction lengths are sometimes expressed as full-word (32 bits in length) or half-word (16 bits in length).
In telecommunication, the bit rate is the number of bits that are transmitted in a given time period, usually a second.
|Data Term||Relative Size||Size (Bytes)|
|Bit||0 or 1||1/8|
|Byte (B)||8 bits||1 byte|
|Kilobyte (KB)||1024 B||103 bytes|
|Megabyte (MB)||1024 KB||106 bytes|
|Gigabyte (GB)||1024 MB||109 bytes|
|Terabyte (TB)||1024 GB||1012 bytes|
|Petabyte (PB)||1024 TB||1015 bytes|
|Exabyte (EB)||1024 PB||1018 bytes|
|Zettabyte (ZB)||1024 EB||1021 bytes|
|Yottabyte (YB)||1024 ZB||1024 bytes|