What is this?
Frames are the set of assumptions we agree to in a negotiating or persuading situation.
Why is this important?
As a party to any persuasive endeavor or negotiation it is important that we exercise our ability to set (or at least help to formulate) the ground rules by which we will conduct our negotiation - or the assumptions that will form the common basis for our interaction. For example, many times people will be concerned about driving their own agenda or protecting their own turf as we begin interacting with them. In these instances it can be very beneficial to diffuse this attitude (which happens to be a part of their frame) by suggesting that we share a common objective or set of values.
A good basic and generic frame is to openly suggest the the goal of the conversation or exchange is to generate mutual benefit for one another - a win/win outcome. Of course, if you are not sincere in making a suggestion such as this the other person is likely (and hopefully) going to see right through your fraudulent ploy. When used sincerely this tool is very useful for speeding up persuasive conversations and eliminating unnecessary obstacles to the completion of exchanges.