Sonnet 18 (also known as "Shall I compare thee to a summer's day") is one of the best-known of the 154 sonnets written by English poet and playwright William Shakespeare.
In the sonnet, the speaker asks whether he should compare the Fair Youth to a summer's day, but notes that he has qualities that surpass a summer's day, which is one of the themes of the poem. He also notes the qualities of a summer day are subject to change and will eventually diminish. The speaker then states that the Fair Youth will live forever in the lines of the poem, as long as it can be read. There is an irony being expressed in this sonnet: it is not the actual young man who will be eternalized, but the description of him contained in the poem, and the poem contains scant or no description of the young man, but instead contains vivid and lasting descriptions of a summer day, which the young man is supposed to outlive.
