English uses many contractions. They're words which reduce two words to one. Contractions are especially common in casual speech and writing.
Many contractions include personal pronouns and the negative adverb not. Examples include I'm, you're, we're, aren't and can't. With negative contractions, two forms are often possible. For example, you aren't and you're not are both acceptable. The verb might, however, never contracts.
Contractions are very common in English. However, they're avoided in formal language. Many contractions include a personal pronoun and verb.