any of several organic compounds widely distributed as pigments in plants and animals and converted in the livers of many animals into vitamin A. These pigments are unsaturated hydrocarbons (having many double bonds), belonging to the isoprenoid series. Several isomeric forms (same formula but different molecular structures) are subsumed under the name.

In plants, carotenes impart yellow, orange, or red colours to flowers (dandelion, marigold), fruits (pumpkin, apricot), and roots (carrot, sweet potato). In animals they are visible in fats (butter), egg yolks, feathers (canary), and shells (lobster).

The most important provitamin (source of the vitamin) A is β-carotene, first isolated from carrots in 1910. Studies by several scientists culminated in its synthesis in 1950.