In 1962, Philips invented the Compact Cassette medium for audio storage, introducing it in Europe on 30 August 1963 (at the Berlin Radio Show), and in the United States (under the Norelco brand) in November 1964, with the trademark name Compact Cassette. The team at Philips was led by Lou Ottens in Hasselt, Belgium.

Although there were other magnetic tape cartridge systems, Philips' Compact Cassette became dominant as a result of Philips' decision in the face of pressure from Sony to license the format free of charge. Philips also released the Norelco Carry-Corder 150 recorder/player in the U.S. in November 1964. By 1966 over 250,000 recorders had been sold in the US alone and Japan soon became the major source of recorders. By 1968, 85 manufacturers had sold over 2.4 million players.

In the early years, sound quality was mediocre, but it improved dramatically by the early 1970s when it caught up with the quality of 8-track tape and kept improving. The Compact Cassette went on to become a popular (and re-recordable) alternative to the 12-inch vinyl LP during the late 1970s.

From Wikipedia.