Understanding body language
The technique of "reading" people is used frequently. For example, the idea of mirroring body language to put people at ease is commonly used in interviews. Mirroring the body language of someone else indicates that they are understood.
Body language signals may have a goal other than communication. Both people would keep this in mind. Observers limit the weight they place on non-verbal cues. Signalers clarify their signals to indicate the biological origin of their actions. One example would be yawning,showing lack of interest,desire to change the topic.
 Physical expression
Physical expressions like waving, pointing, touching and slouching are all forms of nonverbal communication. The study of body movement and expression is known as kinesics. Humans move their bodies when communicating because, as research has shown, it helps "ease the mental effort when communication is difficult." Physical expressions reveal many things about the person using them. For example, gestures can emphasize a point or relay a message, posture can reveal boredom or great interest, and touch can convey encouragement or caution.
Some people use and understand body language differently, or not at all. Interpreting their gestures and facial expressions (or lack thereof) in the context of normal body language usually leads to misunderstandings and misinterpretations (especially if body language is given priority over spoken language). It should also be stated that people from different cultures can interpret body language in different ways.
 How prevalent is non-verbal communication in humans?
Some researchers[who?] put the level of nonverbal communication as high as 80 percent of all communication when it could be at around 50-65 percent. Different studies have found differing amounts, with some studies showing that facial communication is believed 4.3 times more often than verbal meaning, and another finding that verbal communication in a flat tone is 4 times more likely to be understood than a pure facial expression. Albert Mehrabian is noted for finding a 7%-38%-55% rule, supposedly denoting how much communication was conferred by words, tone, and body language. However he was only referring to cases of expressing feelings or attitudes.
 Body language and space
Interpersonal space refers to the psychological "bubble" that we can imagine exists when someone is standing way too close to us. Research has revealed that there are four different zones of interpersonal space. The first zone is called intimate distance and ranges from touching to about eighteen inches (46 cm) apart. Intimate distance is the space around us that we reserve for lovers, children, as well as close family members and friends. The second zone is called personal distance and begins about an arm's length away; starting around eighteen inches (46 cm) from our person and ending about four feet (122 cm) away. We use personal distance in conversations with friends, to chat with associates, and in group discussions. The third zone of interpersonal space is called social distance and is the area that ranges from four to eight feet (1.2 m - 2.4 m) away from you. Social distance is reserved for strangers, newly formed groups, and new acquaintances. The fourth identified zone of space is public distance and includes anything more than eight feet (2.4 m) away from you. This zone is used for speeches, lectures, and theater; essentially, public distance is that range reserved for larger audiences.
 Unintentional gestures
Recently, there has been huge interest in studying human behavioral clues that could be useful for developing an interactive and adaptive human-machine system. Unintentional human gestures such as making an eye rub, a chin rest, a lip touch, a nose itch, a head scratch, an ear scratch, crossing arms, and a finger lock have been found conveying some useful information in specific context. Some researchers have tried to extract such gestures in a specific context of educational applications. In poker games, such gestures are referred to as "tells" and are useful to players for detecting deception or behavioral patterns in an opponent.