What is a retainer or match contract?

Agreement whereby a company hires the services of a commercial promotion agency for a specified time — a year, a few months, or a few hours — in exchange for a specific amount and under certain conditions. It differs from project contracts in that the agency, generally, does not limit itself to executing a single job, but rather all those that arise throughout the contracted period.

Other denominations:
Iguala contract, resource package fees, retainer fees