Sir Timothy John Berners-Lee (born 8 June 1955), also known as TimBL, is an English computer scientist best known as the inventor of the World Wide Web, HTML, the URL system, and HTTP. He is a professorial research fellow at the University of Oxford and a professor emeritus at the Massachusetts Institute of Technology (MIT).

Berners-Lee proposed an information management system on 12 March 1989 and implemented the first successful communication between a Hypertext Transfer Protocol (HTTP) client and server via the Internet in mid-November. He devised and implemented the first Web browser and Web server and helped foster the Web's subsequent development. He is the founder and emeritus director of the World Wide Web Consortium (W3C), which oversees the continued development of the Web. He co-founded (with Rosemary Leith) the World Wide Web Foundation. In 2009, he was elected Foreign Associate of the National Academy of Sciences.

Berners-Lee was previously a senior researcher and holder of the 3Com founder's chair at the MIT Computer Science and Artificial Intelligence Laboratory (CSAIL). He is a director of the Web Science Research Initiative (WSRI) and a member of the advisory board of the MIT Center for Collective Intelligence. In 2011, he was named a member of the board of trustees of the Ford Foundation. He is a founder and president of the Open Data Institute and is an advisor at social network MeWe. In 2004, Berners-Lee was knighted by Queen Elizabeth II for his pioneering work. He received the 2016 Turing Award "for inventing the World Wide Web, the first web browser, and the fundamental protocols and algorithms allowing the Web to scale". He was named in Time magazine's list of the 100 Most Important People of the 20th century and has received a number of other accolades for his invention.

Berners-Lee was born in London on 8 June 1955, the son of mathematicians and computer scientists Mary Lee Berners-Lee (née Woods; 1924–2017) and Conway Berners-Lee (1921–2019). His parents were both from Birmingham and worked on the Ferranti Mark 1, the first commercially built computer. He has three younger siblings; his brother, Mike, is a professor of ecology and climate change management.

Berners-Lee attended Sheen Mount Primary School, then Emanuel School (a direct grant grammar school at the time) from 1969 to 1973. A keen trainspotter as a child, he learnt about electronics from tinkering with a model railway.

In 1976, Berners-Lee took a first in physics from The Queen's College, Oxford. While there, he made a computer out of an old television set he had purchased from a repair shop.

After graduation, Berners-Lee worked as an engineer at the telecommunications company Plessey in Poole, Dorset. In 1978, he joined D. G. Nash in Ferndown, Dorset, where he helped create typesetting software for printers.

Berners-Lee worked as an independent contractor at CERN from June to December 1980. While in Geneva, he proposed a project based on the concept of hypertext, to facilitate sharing and updating information among researchers. To demonstrate it, he built a prototype system named ENQUIRE.