block

A block is a solid piece of material with flat surfaces, typically with a roughly rectangular shape. Blocks are produced by cutting, carving, or casting and are used as building units, weights, or spacers. Common materials include wood, stone, and concrete.

In construction, blocks such as concrete masonry units (CMUs) or breeze blocks are used to form walls and barriers. Blocks may be hollow to reduce weight and improve insulation; masonry blocks vary in size and strength and may be reinforced with steel.

In urban planning, a city block denotes a defined parcel of land bounded by streets, usually rectangular and containing multiple properties. Block arrangements determine streetscape, lot sizes, and access.

In computing, a data block is a fixed-size unit of storage in a file system or memory. File systems allocate space in blocks; fragmentation can occur when files do not neatly fill blocks. Block devices are hardware or virtual devices exposing a block abstraction.

In blockchain technology, a block is a package of transactions that is added to a chain after validation. Each block contains a header with a timestamp, a cryptographic hash of the previous block, and a set of transactions; blocks form a blockchain. Mining or validation processes determine the order and integrity.

In programming, a block is a group of statements that execute together, often delimited by braces or indentation. Blocks define scope, control structures, and the organization of code. The term is used across languages with varying syntax and rules.