Bitumen is a category of organic liquids which are highly viscous, black, sticky and wholly soluble in carbon disulfide. Asphalt and tar are the most common forms of bitumen.

In British English, 'bitumen' is often used interchangeably with both 'asphalt' and 'tar'. In American English, 'bitumen' is most commonly used in engineering jargon to explicitly include both asphalt- and tar-based materials. In Australian English, 'bitumen' is used as the generic term for road surfaces.

Bitumen is obtained by fractional distillation of crude oil. Bitumen being the heaviest and being the fraction with the highest boiling point, it appears as the bottommost fraction.

Bitumen is primarily used in creating asphalt for roads, and used raw as a substance to repair roads. It may also be refined into oil, but a cost-effective way of doing this has yet to be discovered.

Vessels for the heating of bitumen or bituminous compounds are a usual exclusion of public liability insurance policies.