compress

Compress is a verb referring to the act of reducing the volume or space occupied by an object or substance by applying pressure. In everyday language it can describe squeezing, compacting, or condensing. In physics and engineering, compression describes a state produced by applying a compressive force, and materials are characterized by compressibility, the extent to which their volume decreases under pressure. The reciprocal property is stiffness, often quantified by bulk modulus; gases are highly compressible, whereas liquids and solids are less so. In mechanical systems, components such as pistons and cylinders are designed to withstand compressive loads, and fluids can act under pressure in hydraulic and pneumatic devices.

In computing and information technology, compress refers to reducing the amount of data required to represent information. Data compression uses algorithms to remove redundancy, producing a compressed representation that can be restored by decompression. Lossless compression preserves exact original data, while lossy compression sacrifices some information for higher reduction, common in audio, image, and video formats. Typical techniques include entropy encoding, dictionary methods, and transform coding. The efficiency of compression is quantified by the compression ratio, the size of the original data divided by the size of the compressed data.

Additionally, compression concepts appear in thermodynamics, astrophysics, and fluid dynamics, where compressible flow and shock waves are studied. The term is also used metaphorically to describe actions that compress or consolidate information, resources, or space.