Electronic mail was introduced in the early 1970s along with communication protocol still in use today: Transmission Control Protocol/Internet Protocol (TCP/IP), and File Transfer Protocol (FTP). The domain name system was introduced in 1985 with the extensions of .com, .org, .net, .gov, .mil and .edu. Then in 1989, Tim Berners-Lee of CERN (European Laboratory for Particle Physics) developed a new technique for distributing information on the Internet he called the World Wide Web. Based on hypertext, the web permits the user to connect from one document to another at different sites on the Internet via hyperlinks (specially programmed words, phrases, buttons, or graphics). Unlike other Internet protocols, such as FTP and email, the Web is accessible through a graphical user interface. This brought the development of web browsers that could decipher coding in documents and display them according to a set of instructions called hypertext markup language. Meanwhile, the first efforts to index the contents of the Internet were introduced in the early 90s.