Bits, Bytes, and Words

• Each 0 or 1 in the binary system is called a bit (for binary digit).
• The bit is the basic unit for storing data in computer memory (0 means off, 1 means on). 
  Since a bit is always either on or off, the computer is always storing some kind of data.
• Single bits cannot store all the numbers, letters, and special characters (such as $ and ?) that must be processed by a computer. 
  The bits are put together in a group called a byte (pronounced "bite").
• A byte usually holds 8 bits and represents one entity, like a character of data such as a letter, digit, or special character.
• Bytes are usually expressed by the thousands, millions, and billions: kilobytes (KB or K), megabytes (MB), and gigabytes (GB), respectively. 
  A kilobyte (KB) is 1,024 bytes (2¹⁰). 
  A megabyte (MB) is 1,024,000 bytes (2²⁰) or 1,024 KB. 
  A gigabyte (GB) can be 1,024,000,000 bytes (2³⁰), 1,024,000 KB, or 1,024 MB.
  A terabyte (TB) : 1 TB = 2⁴⁰bytes = 1024 GB.
• Personal computer memory may have 64 MB and more.
• Megahertz is a measurement of the speed of the microprocessor.
• A computer word is defined as the number of bits that constitute a common unit of data, as defined by the computer system. 
  The size is from 8 bits to 32 or 64 bits.  The larger the word, the more powerful the computer.
• The parts of a computer are connected by collections of wires called buses or bus lines. 
  Each has a certain number of data paths along which bits can travel; the number of data paths is usually related to the number of bits in the word size.