Crystal is a proponent of Internet linguistics and has also been involved in Shakespeare productions, providing guidance on original pronunciation.

He remained estranged from and ignorant of his father for most of his childhood, but later learnt (through work contacts and a half-brother) of the life and career of Samuel Crystal in London, and of his half-Jewish heritage.

He grew up with his mother in Holyhead, North Wales, and Liverpool, England, where he attended St Mary's College from 1951.

[5] Retired from full-time academia, he works as a writer, editor and consultant, and contributes to television and radio broadcasts.

[12] He has published several books for the general reader about linguistics and the English language, which use varied graphics and short essays to communicate technical material in an accessible manner.

[15] In 2009 Routledge published his autobiographical memoir Just a Phrase I'm Going Through: My Life in Language, which was released simultaneously with a DVD of three of his lectures.

The company's iSense and Sitescreen products are based upon the patented Global Data Model, a complex semantic network that Crystal devised in the early 1980s and was adapted for use on the Internet in the mid 1990s.