Shakespeare wrote 154 sonnets, or short poems, that were all published together in 1609. These sonnets can be split into two groups: the first 126 are about a young man, who we call the Fair Youth, and the rest are about a woman called the Dark Lady.
In these sonnets, Shakespeare talks about many things like love, beauty, time, and how life doesn't last forever. But love is the main thing he talks about. He looks at love in different ways, like romantic love, friendship, and how time changes things.
Sonnet 18 is one of these poems and it's very famous. It's special because it talks about love, beauty, and how things don't last forever. People love it because it's beautiful and has themes that never get old.