MSX is a standardized home computer architecture, announced by ASCII Corporation on June 16, 1983. It was initially conceived by Microsoft as a product for the Eastern sector, and jointly marketed by Kazuhiko Nishi, the director at ASCII Corporation. Microsoft and Nishi conceived the project as an attempt to create unified standards among various home computing system manufacturers of the period, in the same fashion as the VHS standard for home video tape machines. The first MSX computer sold to the public was a Mitsubishi ML-8000, released on October 21, 1983, thus marking its official release date.

MSX systems were popular in Japan and several other countries. Eventually, 9 million MSX units were sold worldwide, including 7 million in Japan alone. Despite Microsoft's involvement, few MSX-based machines were released in the United States.

The meaning of the acronym MSX remains a matter of debate. In 2001, Kazuhiko Nishi recalled that many assumed that it was derived from "Microsoft Extended", referring to the built-in Microsoft Extended BASIC (MSX BASIC). Others believed that it stood for "Matsushita-Sony". Nishi said that the team's original definition was "Machines with Software eXchangeability", although in 1985 he said it was named after the MX missile. According to his book in 2020, he considered the name of the new standard should consist of three letters, like VHS. He felt "MSX" was fit because it means "the next of Microsoft", and it also contains the first letters of Matsushita (Panasonic) and Sony.

Before the success of Nintendo's Family Computer, the MSX was the platform that major Japanese game studios such as Konami and Hudson Soft developed for. The Metal Gear series, for example, was first written for MSX hardware.