A little more than 40 years ago Douglas Engelbart introduced his "X–Y position indicator for a display system"—more commonly known today as the computer mouse—during a 90-minute presentation on a "computer-based, interactive, multiconsole display system" at the Stanford Research Institute (SRI) in Menlo Park, Calif. This event—attended by some 1,000 computer professionals—would later be called by many the "mother of all demos" and would introduce a number of computing capabilities largely taken for granted today: the mouse, hypertext, object addressing and dynamic file linking.

Engelbart, now 84, filed the patent in 1967 but had to wait three years for the U.S. to acknowledge his technology, which provided the tool needed to navigate graphics-filled computer screens with a simple motion of the hand rather than by wading through screens filled with green-tinted text using keys or a light pencil pressed up against a computer monitor. "I don't know why we call it a mouse," he said during the demo. "It started that way, and we never did change it."

The original mouse, housed in a wooden box twice as high as today's mice and with three buttons on top, moved with the help of two wheels on its underside rather than a rubber trackball. The wheels—one for the horizontal and another for the vertical—sat at right angles. When the mouse was moved, the vertical wheel rolled along the surface while the horizontal wheel slid sideways. Mice grew more ergonomic over time and have adopted trackballs, lasers and LEDs, but the premise is the same—the computer records both the distance and speed at which the mouse travels and turns that information into binary code that it can understand and plot on a display screen.

Engelbart originally invented the mouse as a way to navigate his oNLine System (NLS), a precursor of the Internet that allowed computer users to share information stored on their computers. NLS, which Engelbart developed with funding from the U.S. Department of Defense's Advanced Research Projects Agency (ARPA—now DARPA), was also the first system to successfully use hypertext to link files (making information available through a click of the mouse).

Because his patent for the mouse expired before it became widely used with personal computers in the mid-1980s, Engelbart garnered neither widespread recognition nor royalties for his invention. Mouse technology found its way from Engelbart's lab to the Xerox Corp.'s Palo Alto Research Center (PARC) in 1971, when Bill English, a computer engineer who had worked for Engelbart at SRI, joined PARC. Xerox was the first to sell a computer system that came with a mouse—the 8010 Star Information System in 1981, but the term "mouse" wouldn't become a part of the modern lexicon until Apple made it standard equipment with its original Macintosh, which debuted in 1984. The emergence of the Microsoft Windows operating system and Web browsers hastened the mouse's pervasiveness throughout the 1990s and into the first decade of the 21st century.

Engelbart's own work at SRI came to an end in 1989, when McDonnell Douglas Corp. (his ultimate employer there after his division at SRI had changed owners a few times) shut down his lab. That year, Engelbart formed the Bootstrap Institute (now known as the Doug Engelbart Institute) , a consulting firm in Menlo Park through which he still encourages researchers to share findings and build on one another's achievements.

Logitech claims to have manufactured one billion mice, which "speaks volumes for the success of this pointing device and the dominance of the graphical user interface of which it is an integral part," Gartner Blog Network analyst Steve Prentice blogged in December. Still, he adds, mice don't factor into a future where touch-screen smart phones, touch-pad laptops and video game controllers with embedded accelerometers (such as those shipped with Nintendo's Wii) rule the day. His prediction: the mouse is an endangered species with less than five years before it joins the ranks of the green screen, punch cards and other computer technologies now honorably retired to technology museums after years of faithful service on desktops everywhere.