blob

Blob is a term used for a shapeless, amorphous mass. In everyday language it denotes a soft, jelly-like lump without a clearly defined form. The word is thought to be onomatopoeic, mirroring the irregular, formless shape, and it entered English in the 19th century.

In computing, BLOB stands for Binary Large Object, a data type for storing large binary data such as images, audio, or video within a database or file system. BLOBs are typically accessed as streams or through APIs that read and write data in chunks. They can complicate indexing and querying, and managers may store BLOBs outside the database in a filesystem or object storage. Performance considerations include fragmentation, backup, transfer costs, and the choice between inline storage versus external references.

In computer vision, a blob refers to a connected region of an image that differs in properties like brightness or color from its surroundings. Blob detection algorithms identify such regions at multiple scales to locate features for tasks such as object recognition, segmentation, and tracking.

In biology and popular science, the term often appears in reference to slime molds such as Physarum polycephalum, which can form a mobile, jelly-like mass used in experiments on network optimization and collective behavior. The word also shows up in popular culture as The Blob, a 1958 American science fiction film about a gelatinous alien that consumes everything in its path.

Beyond these uses, blob generally denotes a flexible, formless entity applied across disciplines to describe amorphous, viscoelastic, or data-containing masses.