California Proof Of Service is a legal document that proves that a legal document has been delivered to the correct person. It is used for a variety of legal purposes, including filing documents to the court, serving notice of a lawsuit, and providing evidence of a debt or contract. There are three types of California Proof Of Service: Personal Service, Substituted Service, and Service By Mail. Personal Service requires a process server to physically deliver the document to the person to whom it is addressed. Substituted Service uses an alternate method to deliver the document, such as leaving it with a person of suitable age and discretion at the defendant’s residence or place of business. Finally, Service By Mail requires the process server to mail the document to the defendant via certified mail or registered mail, with return receipt requested.