Negotiation is a dialogue

Dialogue

Dialogue is a literary and theatrical form consisting of a written or spoken conversational exchange between two or more people....

 between two or more people or parties, intended to reach an understanding, resolve point of difference, or gain advantage in outcome of dialogue, to produce an agreement upon courses of action, to bargain for individual or collective advantage

Collective bargaining

Collective bargaining is a process of negotiations between employers and the representatives of a unit of employees aimed at reaching agreements that regulate working conditions...

, to craft outcomes to satisfy various interests of two people/parties involved in negotiation process. Negotiation is a process where each party involved in negotiating tries to gain an advantage for themselves by the end of the process.