- May 13-17: The 1991 Worldwide Developers Conference is held in San Jose, California, where System 7 is released.
- August 6: The first website of the World Wide Web goes live on a NeXT Computer.
- August 28: The first email from space was sent from a Macintosh Portable running AppleLink aboard the Space Shuttle Atlantis.
- October 2: Apple Computer, IBM, and Motorola jointly form the AIM alliance, which was created to developed a new computing platform which would be known as PowerPC.
- October 21: The Macintosh Classic II and first PowerBooks are released to the public.
- December: QuickTime 1.0 is released.
- MacAddict (later named Mac|Life) calls 1989 to 1991 the "golden age of the Macintosh".