The Maryland Certificate of Service is a document used to prove service of process in the state of Maryland. It is used to certify that a party was properly served with a legal document, such as a summons or complaint. There are two types of Maryland Certificates of Service: Certificate of Service by Mail, and Certificate of Service by Hand Delivery. The Certificate of Service by Mail is used when a legal document is served by mail, and the Certificate of Service by Hand Delivery is used when a legal document is served in person. The document must be signed by the individual who served the legal document and must include the date, name and address of the person served, and the nature of the document served. The Certificate of Service must be returned to the court or party who initiated the service.