This Practice Note examines the nature of performance bonds and their use as financial security on construction projects. It looks at why building contracts commonly require contractors to provide a bond from a surety to the employer and where they fit into the documentation commonly required for a project. It covers the structure of a performance bond, the different types of bond and the differences between them. It also reviews key provisions which should be included for a performance bond to be effective, including the maximum amount of a bond, when it should expire and notice provisions.