A partner program (also called a partnership program) is a business initiative that connects companies to multiple types of partners who provide marketing support, leads, and ultimately, revenue. Partners can consist of marketing partners, referral partners, or reseller partners, affiliate partners and more (learn the right type of partner program for you).
Partner programs are established to leverage the strengths and resources of each participant, enabling them to work together towards common goals. Ultimately, monetary rewards are the key to almost every successful partner program as partners are rewarded through incentives (either monetary or through perks and rewards).
Example: All different types of partner programs (referral, affiliate, reseller, agency) are designed to drive revenue, but they often have many different methods of execution, and work will in tandem with each other.