When interacting with user interfaces, users have to bridge the gap between their goals expressed in mental terms and the interface's structures and functions expressed in physical terms. This gap has been characterized as the "Gulf of Execution", and it may imply significant cognitive processing on the users' side in order for them to successfully accomplish their goals.

If user interfaces could understand, at a high-level, our goals, our problems, and our social procedures, users could have cognitively accessible, dynamic interfaces accommodating their unique needs, beyond the range of applications anticipated by the designers.

For computers to realize such a goal-oriented paradigm,

• They must have access to information about the world that human users take for granted. This information, which forms the basis for goal-directed computer interactions, is common sense knowledge.
• They must provide for algorithms and techniques that are capable of acquiring and structuring knowledge about user goals.
• They must have adequate means to represent knowledge about user goals in a way that allows for reasoning and inference about them.
• They must provide for user interfaces that effectively map users' goals on the computer's functionalities and structures.