A partnership is an arrangement where parties agree to cooperate to advance their mutual interests.

Since humans are social beings, partnerships between individuals, businesses, interest-based organizations, schools, governments, and varied combinations thereof, have always been and remain commonplace. In the most frequently associated instance of the term, a partnership is formed between one or more businesses in which partners (owners) co-labor to achieve and share profits and losses (see business partners). Partnerships are also common regardless of and among sectors. Non-profit, religious, and political organizations, may partner together to increase the likelihood of each achieving their mission and to amplify their reach. In what is usually called an alliance, governments may partner to achieve their national interests, sometimes against allied governments who hold contrary interests, such as occurred during World War II and the Cold War. In education, accrediting agencies increasingly evaluate schools by the level and quality of their partnerships with other schools and a variety of other entities across societal sectors. Partnerships also occur at personal levels, such as when two or more individuals agree to domicile together, while other partnerships are not only personal but private, known only to the involved parties.