1. used to refer back to a thing or animal that is the subject of the sentence
Usage: reflexive pronoun
2. used for emphasis to refer to a particular thing or animal
Usage: emphatic use
3. without help from anyone or anything else; alone
Usage: often used with ‘by’

Examples

• The cat cleaned itself after eating.
• The machine turns itself off automatically.
• The house itself is beautiful, but the yard needs work.
• The problem will solve itself over time.
• The door opened by itself.
• The company prides itself on customer service.
• The building itself is historic.