Shakespeare uses some old words that are no longer used today. He also wrote very formally. The combination of these two factors makes it difficult for modern students to understand.
Sonnets written in English are most commonly written in <u>iambic pentameter.</u>
This means that there are ten syllables in a line (penta means five, and a meter has two syllables, so five times two is ten), and iambic refers to the fact that the first syllable is always unstressed, and the one which follows it is stressed.
