What were cassette tapes used for?
To record and play music .
an electronic item that plays cassette tapes. A "tape deck" is a device used to play cassette or 8-track tapes. They are fairly obsolete now, but until CDs became the rage, tapes were used regularly. There were also 4 track tape decks. Magnovox was a leader in producing tape decks. You would get them installed in your car just as you would CD players.