Cats is a musical by Andrew Lloyd Webber, who wrote the music. Most of the words come from Old Possum's Book of Practical Cats, which is a book of poems by T.S. Eliot. In this musical, the cats act like people and have different personalities. Many things happen in this musical, but one of the important things is that a cat is chosen to go to the "Heaviside Layer", which is like a heaven for cats.
Cats was first shown in London in 1981, with Elaine Paige first playing the role of Grizabella who sings "Memory", a memorable song in the show. It was shown on Broadway starting in 1982. The musical has since been made into many languages, and it has been shown around the world.