Bargaining is the back and forth process of negotiation in order to make an agreement between two parties.
For example, it is common to bargain at a flea market or yard sale. You counter the asking price with a lower one, the seller may counter that with a price higher than that but lower than the original, and so on. Eventually an agreement will be reached that both parties feel is fair. In psychology bargaining is used in the Kubler-Ross model which is also known as the five stages of grief (Denial, anger, bargaining, depression, and acceptance). A person will try to avoid the bad situation by trying to bargain ("If I do this, then it won't happen.)