In negotiation theory, the best alternative to a negotiated agreement or BATNA is the course of action that will be taken by a party if the current negotiations fail and an agreement cannot be reached. Negotiation is the process whereby interested parties resolve disputes, agree upon courses of action, bargain for individual or collective advantage, and/or attempt to craft outcomes which serve their mutual interests. ... Look up Agreement in Wiktionary, the free dictionary An agreement may be an agreement in beliefs, rules, practices (policies), or conduct. ...

If the current negotiations are giving you less value than your BATNA, there is no point in proceeding. Prior to the start of negotiations, the parties should have ascertained their own individual BATNAs.

BATNA was developed by negotiation researchers Roger Fisher and Bill Ury of the Harvard Program on Negotiation (PON), in their series of books on Principled Negotiation that started with Getting to YES. Nobel Laureate John Forbes Nash has included such ideas in his early undergraduate research. Negotiation and conflict resolution expert Roger Fisher is the co-author (along with Bill Ury) of the classic book on win-win negotiation called Getting to YES. Fisher, a professor at Harvard Law School, says he started by asking the question What advice could I give to both parties in... Principled Negotiation is the approach to negotiation developed by Roger Fisher, Bill Ury, and others, first described in the book Getting to YES. In concept, Principled Negotiation is a win-win approach where the goal is to reach a lasting agreement, rather than traditional positional (win-lose) bargaining. ... John Forbes Nash Jr. ...

An example might be if I have a written offer from CarMax to buy my car for $100 dollars, my BATNA when dealing with other potential purchasers would be $100 since I can get $100 for my car even without reaching an agreement with such alternative purchaser.

A party should generally never accept a worse resolution than such their BATNA. Care should be taken, however, to ensure that deals are accurately valued, taking into account all considerations (such as relationship value, time value of money, likelihood that the other party will live up to their side of the bargain, etc.) These other considerations are very difficult to value, since they are often based on uncertain considerations, rather than easily measurable and quantifiable factors.

Examples of other offers that might or might not be better than the BATNA in the example above might be:

An offer of $90 by a close relative (is the goodwill generated worth $10 or more?)

An offer of $125 in 45 days (what are the chances of this future commitment falling through, and would my prior BATNA ($100) still be available if it did?)

An offer from another dealer to offset $150 against the price of a new car (do I want to buy a new car right now, the offered car in particular? Also, is the probably minuscule reduction in monthly payments worth $100 to me today?)