Douglas Carl Engelbart (January 30, 1925 – July 2, 2013) was an American engineer, inventor, and a pioneer in many aspects of computer science. He is best known for his work on founding the field of human–computer interaction, particularly while at his Augmentation Research Center Lab in SRI International, which resulted in creation of the computer mouse, and the development of hypertext, networked computers, and precursors to graphical user interfaces. These were demonstrated at The Mother of All Demos in 1968. Engelbart's law, the observation that the intrinsic rate of human performance is exponential, is named after him.
The "oN-Line System" (NLS) developed by the Augmentation Research Center under Engelbart's guidance with funding mostly from the Advanced Research Projects Agency (ARPA), later renamed Defense Advanced Research Projects Agency (DARPA), demonstrated many technologies, most of which are now in widespread use; it included the computer mouse, bitmapped screens, word processing, and hypertext; all of which were displayed at "The Mother of All Demos" in 1968.