Short answers, pulled from the story.
The Recording Industry Association of America defines an EP as a release under 30 minutes containing three to five songs for the purposes of certification. This classification distinguishes the format from albums which require five or more different songs and a running time of over 15 minutes according to The Recording Academy's rules for the Grammy Awards.
RCA Victor introduced the 45 rpm Extended Play record in 1952 as a technical solution to a market war. The company narrowed the grooves and lowered the cutting levels to fit up to 7.5 minutes of audio on each side of a 7-inch disc. This innovation allowed record labels to release entire albums split across multiple 7-inch discs before the widespread adoption of triple-speed phonographs.
The Buzzcocks released the Spiral Scratch EP in 1977 as a pivotal moment in the history of the format. This release demonstrated the EP's ability to serve as a vehicle for original material rather than just a collection of singles. The format was particularly popular with punk and indie bands who appreciated its lower production costs and the ability to release music quickly.
The Official Chart Company classifies any record with more than four tracks or with a playing time of more than 25 minutes as an album for sales-chart purposes. This classification creates ambiguity where the same release can be classified differently depending on the context. The format's definition has been complicated by the advent of CDs, music downloads, and music streaming.
The first double EP released in Britain was the Beatles' Magical Mystery Tour film soundtrack. This release contained six songs spread over two 7-inch discs and was packaged with a lavish color booklet. The format offered a unique solution for artists who wanted to release a substantial amount of material without committing to a full-length album.