讨价还价是指在买卖商品或服务中，两方之间对对方提出的条件的谈判。讨价还价是固定价格的替代方式。理想情况下，如果零售者的成本并没有那幺高而且允许讨价还价的话，可以大概看出买家购买的意欲。因为这种价格歧视，卖家可以得到更高的利润，卖家可能给一个急于购买的人（有钱人或更想要）出更高的价格。因为讨价还价的成本高于受益，讨价还价已经在某些程度上消失了，尤其在常见的零售商品中。不过对于昂贵的商品，如汽车，讨价还价还是很常见。

尽管与讨价还价没有任何关系也没有关于价格的谈判，库伯勒-罗丝模型的第三阶段（俗称垂死的阶段）也叫做讨价还价。

Bargaining or haggling is a type of negotiation in which the buyer and seller of a good or service debate the price and exact nature of a transaction. If the bargaining produces agreement on terms, the transaction takes place. Bargaining is an alternative pricing strategy to fixed prices. Optimally, if it costs the retailer nothing to engage and allow bargaining, he/she can divine the buyer's willingness to spend. It allows for capturing more consumer surplus as it allows price discrimination, a process whereby a seller can charge a higher price to one buyer who is more eager (by being richer or more desperate). Haggling has largely disappeared in parts of the world where the cost to haggle exceeds the gain to retailers for most common retail items. However, for expensive goods sold to uninformed buyers such as automobiles, bargaining can remain commonplace.