Negotiation is a dialogue between two or more people or parties intended to reach an understanding, resolve points of difference, to gain advantage for an individual or collective, or to craft outcomes to satisfy various interests. Negotiation occurs in business, non-profit organizations, government branches, legal proceedings, among nations and in personal situations such as marriage, divorce, parenting, and everyday life. The study of the subject is called negotiation theory. Professional negotiators are often specialized, such as union negotiators, leverage buyout negotiators, peace negotiators, hostage negotiators, or may work under other titles, such as diplomats, legislators or brokers.