Physical intimacy is sensual proximity or touching. It is an act or reaction, such as an expression of feelings (including close friendship, romantic love or sexual attraction), between people. Examples of physical intimacy include being inside someone's personal space, holding hands, hugging, kissing, caressing and sexual activity.
It is possible to be physically intimate with someone without actually touching them; however, a certain proximity is necessary. For instance, a sustained eye contact is considered a form of physical intimacy, analogous to touching. When a person enters someone else's personal space for the purpose of being intimate, it is physical intimacy, regardless of the lack of actual physical contact.
Most people partake in physical intimacy, which is a natural part of interpersonal relationships and human sexuality, and research has shown it has health benefits. A hug or touch can result in the release of oxytocin, dopamine and serotonin, and in a reduction in stress hormones.
Most people value their personal space and feel discomfort, anger or anxiety when somebody encroaches on their personal space without consent. Entering somebody's personal space is normally an indication of familiarity and intimacy. However, in modern society, especially in crowded urban communities, it is at times difficult to maintain personal space, for example, in a crowded train, elevator or street. Many people find the physical proximity within crowded spaces to be psychologically disturbing and uncomfortable, though it is accepted as a fact of modern life. In an impersonal crowded situation, eye contact tends to be avoided. Even in a crowded place, preserving personal space is important. Non-consensual intimate and sexual contact, such as frotteurism and groping, are unacceptable.
On the other hand, most people occasionally desire physical proximity to others, and will at times welcome a familiar and trusted person into their personal space. When a partner or friend is not available at such a time, some people satisfy this need for human contact in a crowded venue, such as a bar, nightclub, rock concert, street festival, etc.
People who are on a familiar basis may enter into each other's personal space to make physical contact. These can be indicators of affection and trust. The manner in which people display affection is generally different in a public context to a private one. In private, people in an intimate relationship or who are familiar with each other may be at ease with physical contact and displays of affection, which may involve:cuddling,
caressing (e.g. head, hands, arms, back and waist),
tickling (e.g. back and waist),
massage (e.g. neck, shoulders, back, thighs), or
Bonding through intimate, non-sexual contact between platonic friends and family members includes, but is not limited to, holding hands, hugging, cuddling, and kissing on the cheeks.
In public, however and depending on the nature of the relationship between the people, a public display of affection is generally constrained by social norms and can range from a gesture such as a kiss or hug in greeting, to an embrace or holding hands. Maintaining eye contact can be regarded socially and psychologically as analogous to touching.
The term "skinship" (スキンシップ, sukinshippu) originated as a pseudo-English Japanese word (wasei-eigo), which was coined to describe the intimacy, or closeness, between a mother and a child. Today, the word is generally used for bonding through physical contact, such as holding hands, hugging, or parents washing their child at a bath. The earliest citation of this word appears in Nihon Kokugo Daijiten in 1971.
According to Scott Clark, author of a study of Japanese bathing culture, the word is a portmanteau combining "skin" with the last syllable of "friendship". The similarity with the English word 'kinship' suggests a further explanation.
Use of the word "skinship" in English publications seems to focus on the notion of sharing a bath naked, an idea known in Japanese as "naked association" (裸の付き合い, hadaka no tsukiai). It is not clear why the meaning shifted to the parent–child relationship when borrowed back into English.
Inducements towards physical intimacy can come from various sources. During colder seasons, humans as well as other animals seek physical intimacy with one another as a means to apportion thermoregulation. Some forms of physical touch among monkeys and apes, serve multiple functions, including cleaning, treatment of a lice influx or infection and social grooming. Some forms of touch derive from curiosity, such as a Caucasian with straight hair probing the texture of someone with afro-textured kinky hair.
Some forms of physical intimacy may be received negatively. This attitude is especially marked amongst those with haphephobia. One study has shown that there's generally a higher level of physical intimacy allowed between immediate family members than between second-degree relatives. Intimacy norms are usually more negative near erogenous zones. Some jurisdictions may specify this as referring to the genitals, buttocks and female breasts.