Rapport is one of the most important features or characteristics of unconscious human interaction. It is commonality of perspective, being in "sync", being on the same wavelength as the person you are talking to.
There are a number of techniques that are supposed to be beneficial in building rapport such as: matching your body language (ie, posture, gesture, and so forth); maintaining eye contact; and matching breathing rhythm. Some of these techniques are explored in neuro-linguistic programming.
A classic if unusual example of rapport can be found in the book "Uncommon Therapy" by Jay Haley (ISBN 0393310310), about the psychotherapeutic intervention techniques of Milton Erickson. Erickson developed the ability to enter the world view of his patients and, from that vantage point (having established rapport), he was able to make extremely effective interventions (to help his patients overcome life problems).
See also: Similarity (psychology)
