An affidavit of service is a legal document attesting to the delivery of case-related paperwork to one or more parties in a legal dispute. It's used to certify the service of a writ, notice, summons or process, and must include the time and method of delivery via written statement.
An affidavit of service is also known as a proof of service, since it provides evidence of delivery. This is critical since paperwork containing details of a case or judgment must be served to both the plaintiff and defendant. Failure to do so can result in a case being delayed or dismissed, or the awarding of a default judgment based on the judge's discretion.