Britannica is a general knowledge English-language encyclopaedia which is now published exclusively as an online encyclopaedia. It was formerly published by Encyclopædia Britannica, Inc., and other publishers. It was written by about 100 full-time editors and more than 4,000 contributors.
Britannica contains carefully edited articles on all major topics. It fits the ideal purpose of a reference work as a place to get started, or to refer back to as you read and write. The articles in Britannica are written by authors both identifiable and credible. Many articles provide references to books and other sources about the topic covered. Articles are edited for length, the goal being to provide students (and other researchers) with sufficient background information without overwhelming them.
Britannica has been published continuously since 1768, appearing in fifteen official editions. Several editions have been amended with multi-volume "supplements" (3rd, 5th/6th), consisted of previous editions with added supplements (10th, and 12th/13th) or gone drastic re-organizations (15th). In recent years, digital versions of the Britannica have been developed, both online and on optical media. Since the early 1930s, the Britannica has developed several "spin-off" products to leverage its reputation as a reliable reference work and educational tool.