Shakespeare wrote the following four lines in iambic pentameter. As the previous educator has explained, "iambic pentameter" refers to five metrical feet of unstressed and stressed syllables per line.
Shall I/ compare/ thee to/ a sum/mers day?/
Thou art/ more love/ly and/ more tem/per-ate:/
Rough winds/ do shake/ the dar/ling buds/ of May, /
And sum/mer's lease/ hath all/ too short/ a date./
These four lines are interesting in the sense that Shakespeare does not vary from a strict representation of iambic pentameter in each line. There are no caesuras (pauses) or feminine endings (where there is one or more unaccented syllables after the fifth stressed syllable in a line). This is unusual for Shakespeare, perhaps, and demonstrates the speaker's unquestionable devotion to his love and his insistence that her beauty exceeds what nature can offer; he has created a perfectly regular representation of it. The consistent use of iambic pentameter certainly captures the nature of this enduring beauty.