Spinning the Facts
When an artist releases an “LP,” this is short for “Long Play,” which was a full-length album on a 12-inch vinyl record played at 33 RPM (rounds per minute).
The “single” was released on a 7-inch record that played at 45 RPM, also known as “a 45.”
Between the single and the LP in length is the “EP” for “Extended Play,” which typically has 3-6 songs on it.
The 45 RPM record could hold roughly 3 minutes of music per side, and having a 45 record was essential to get an artist’s songs played on the radio and build their fanbase. Accordingly, the 3-minute song became the standard. Despite the near-limitless song length now offered by digital media storage, the vast majority of songs released are still under 5 minutes long.
The “B side” or “flip side” of a 45 RPM record often had a secondary or less radio-ready song on it, though many B-sides songs still became successful on their own right.
Some of the earliest sound recordings were made on wax cylinders (though calling them metal soaps is more chemically accurate), hence the reason records are occasionally called “wax.”
Since about the 1940s, records have been made from the polymer polyvinyl chloride, hence the nickname “vinyl.”