What is an 'additional insured' on a liability policy?

An additional insured is a person or entity (other than the named insured) given coverage under the policy, typically via endorsement, for liability arising out of the named insured's operations or relationship with the additional insured. Common situations: (1) Landlords as additional insureds on tenants' liability policies — protected for claims arising out of the tenant's use of the premises; (2) General contractors as additional insureds on subcontractors' policies — protected for the subcontractor's work; (3) Property owners as additional insureds on contractors' policies during construction; (4) Vendors as additional insureds on manufacturers' policies. Being an additional insured provides direct coverage rights rather than just contractual indemnification. The named insured pays the premium and is the policyowner; the additional insured benefits from the coverage. Coverage scope depends on the specific endorsement form used.