Body language is a type of non-verbal communication in which physical behaviour, as opposed to words, are used to express or convey information. Such behaviour includes facial expressions, body posture, gestures, eye movement, touch and the use of space. Body language exists in both animals and humans, but this article focuses on interpretations of human body language. It is also known as kinesics.

Body language must not be confused with sign language, as, sign languages are full languages like spoken languages and have their own complex grammar systems, as well as being able to exhibit the fundamental properties that exist in all languages. Body language, on the other hand, does not have a grammar and must be interpreted broadly, instead of having an absolute meaning corresponding with a certain movement, so it is not a language like sign language and is simply termed as a "language" due to popular culture.

In a community, there are agreed-upon interpretations of particular behaviour. Interpretations may vary from country to country, or culture to culture. On this note, there is controversy on whether body language is universal. Body language, a subset of nonverbal communication, complements verbal communication in social interaction. In fact, some researchers conclude that nonverbal communication accounts for the majority of information transmitted during interpersonal interactions. It helps to establish the relationship between two people and regulates interaction but can be ambiguous. Hence, it is crucial to accurately read body language to avoid misunderstanding in social interactions.

Oculesics:

Oculesics, a subcategory of body language, is the study of eye movement, eye behaviour, gaze, and eye-related nonverbal communication. As a social or behavioural science, oculesics is a form of nonverbal communication focusing on deriving meaning from eye behaviour, It is also crucial to note that Oculesics is culturally dependent. 

For example, in traditional Anglo-Saxon culture, avoiding eye contact usually portrays a lack of confidence, certainty, or truthfulness. However, in the Latino culture, direct or prolonged eye contact means that you are challenging the individual with whom you are speaking or that you have a romantic interest in the person. Also, in many Asian cultures, prolonged eye contact may be a sign of anger or aggression. 

Haptics:

Haptics, a subcategory of Body Language, is the study of touching and how it is used in communication. As such, handshakes, holding hands, back slapping, high fives, brushing up against someone or pats all have meaning. Based on the body language project, touching is the most developed sense at birth and formulates our initial views of the world. Touching can be used to sooth, for amusement during play, to flirt, to expressing power and maintaining bonds between people such as with baby and mother. Touching can carry distinct emotions and also show the intensity of those emotions. Touch absent of other cues can signal anger, fear, disgust, love, gratitude and sympathy depending on the length and type of touching that is performed. Many factors also contribute to the meaning of touching such as the length of the touch and location on the body in which the touching takes place. Research has also shown that people can accurately decode distinct emotions by merely watching others communicate via touch.

Functional/professional which expresses task-orientation: Donald Walton stated in his book that touching is the ultimate expression of closeness or confidence between two people, but not seen often in business or formal relationships. Touching stresses how special the message is that is being sent by the initiator. "If a word of praise is accompanied by a touch on the shoulder, that’s the gold star on the ribbon, "wrote Walton. 

Social/polite which expresses ritual interaction. A study by Jones and Yarbrough regarded communication with touch as the most intimate and involving form which helps people to keep good relationships with others. For example, Jones and Yarbrough explained that strategic touching is a series of touching usually with an ulterior or hidden motive thus making them seem to be using touch as a game to get someone to do something for them. 

Friendship/warmth which expresses idiosyncratic relationship: Love/intimacy which expresses emotional attachment. Public touch can serve as a ‘tie sign’ that shows others that your partner is “taken”. When a couple is holding hands, putting their arms around each other, this is a ‘tie sign’ showing others that they are together. The use of ‘tie signs’ is used more often by couples in the dating and courtship stages than between their married counterparts according to Burgoon, Buller, and Woodall.

Sexual/arousal which expresses sexual intent. The amount of touching that occurs within a culture is also culturally dependent.

Proxemics:

Another notable area in the nonverbal world of body language is that of spatial relationships, which is also known as Proxemics. Introduced by Edward T. Hall in 1966, proxemics is the study of measurable distances between people as they interact with one another. In the book, Body Language, Julius Fast mentioned that the signals that we send or receive to others through body language are reactions to others’ invasions of our personal territories, which links Proxemics an important part of the body. Fundamentally, body language has seemed like an involuntary and unconscious phenomenon that adds to the process of communication. Despite that, there have been certain areas where the conscious harnessing of body language - both in action and comprehension- have been useful. The use of body language has also seen an increase in application and use commercially, with large volumes of books and guides published designed to teach people how to be conscious of body language, and how to use it to benefit them in certain scenarios. The use of body language can be seen in a wide variety of fields. Body language has its application in instructional teaching in areas such as second-language acquisition and also to enhance the teaching of subjects like mathematics. A related use of body language is as a substitution to verbal language to people who lack the ability to use that, be it because of deafness or aphasia. Body language has also been applied in the process of detecting deceit through micro-expressions, both in law enforcement and even in the world of poker.