Block (data storage)

In computing (specifically data transmission and data storage), block size indicates a nominal size, often expressed in bytes or bits, of a block of data. Data thus structured is said to be blocked. The process of putting data into blocks is called blocking. Blocking is used to the facilitate the handling of the data-stream by the computer program receiving the data. Blocked data is normally read a block at a time. Blocking is almost universally employed when storing data to 9-track magnetic tape.