What is a Certificate of Occupancy?
A certificate of occupancy is a document that proves that a property has complied with all building codes and regulations and is ready to be occupied. A certificate of occupancy is necessary residential/commercial tenants as well as retail stores and its customers.
Example of a Certificate of Occupancy (DCRA | Washington, D.C)

Regardless of municipality/city you are in, the document should list the following:
Address
Description of the property (use and square footage)
Zoning Codes
Property Owner
Relevant permit information (square, lot, permit no.)
City Permit | Washington, D.C. | Permit Expediting