The partnership is the primary non-corporate vehicle for individuals who conduct business on a joint basis. Individual partners are taxed on their income from a partnership as if they were self-employed.
A partnership does not actually exist as a legal entity in its own right: technically it is an amalgamation of individuals so when it conducts business it does this through its individual partners and not as a collective entity. Each partner acts as an agent for the others meaning that that each partner is effectively bound by the actions of the other partners.
Partners are also jointly and separately liable for the debts of their firm. The partnership is a flexible and very private, format which allows firms to decide how to organise internal management and profit sharing and is prevalent among of all kinds of businesses.