One of the key concepts in the book GettingToYes is the "BATNA" or BestAlternativeToNegotiatedAgreement.
An extreme example of a BATNA comes from Carl Hiassen's novel Native Tongue. A mob informant is just about to effect his escape with a suitcase full of cash, when he meets up with the hit man the mob has sent to kill him.
Informant: "See this suitcase full of cash? If you let me go, it's yours."
Hit Man: "It's mine if I don't."
In this case, shooting the informant and taking the money is the BestAlternativeToNegotiatedAgreement.
One of the best ways to improve the outcome of negotiations is improve your BATNA. For example, if the informant also had a gun, the hit man might be willing to negotiate to avoid getting killed himself.
In the job hunting world, ways to improve your BATNA include improving your skills, making your resume more BuzzwordCompliant, and finally having MoreThanOneOffer.
--John Brewer
Only having multiple offers fits as BATNA. BATNA is your "walk-away" alternative. Improving your skills and adding buzzwords improve your trading, but offer nothing in the case of walking away. Having a second offer does.
MoreThanOneOffer is the result (a better BATNA). Improving your skills is one of many ways to reach that better BATNA. -- JB
Being reasonably content with your current position is also a BATNA. You don't have to job search when you don't need a job. That way, if the offer you get isn't good enough, you just stay put.
Part of the NegotiatingPatternLanguage.