Short answers, pulled from the story.
The Altair 8800 was released in 1975 and sat in a garage in Albuquerque, New Mexico. This small circuit board built around the Intel 8080 microprocessor marked the beginning of the global transformation toward personal computing.
Robert Noyce developed the silicon integrated circuit in 1959 while working at Fairchild Semiconductor. This breakthrough followed shortly by the metal-oxide-semiconductor transistor created by Mohamed Atalla and Dawon Kahng at Bell Labs in the early 1960s.
The 1977 trinity consisted of the Commodore PET, the Apple II, and the TRS-80 from Tandy Corporation. The Commodore PET was announced in 1977 and available by mid-October 1977, the Apple II was announced in April 1977 with first units shipping on the 10th of June 1977, and the TRS-80 followed in August 1977.
IBM entered the personal computer market on the 12th of August 1981 with the IBM 5150. This machine was priced at US$1,565 and operated with the Intel 8088 chip using an operating system provided by Microsoft known as MS-DOS.
The World Wide Web was made available for public use in 1991. This event allowed users to access information from anywhere in the world and transformed the personal computer into a gateway to the global information network.
Worldwide sales of PCs began to fall as of 2013 following a trend that started in 2012 when smartphones and tablet computers surpassed PC sales. The decline of Q2 2013 PC shipments marked the fifth straight quarter of falling sales as consumers moved to mobile computing devices.