Personal space is the region surrounding people that they regard as psychologically theirs. Most people value their personal space and feel discomfort, anger, or anxiety when that space is encroached. Permitting a person to enter personal space and entering somebody else's personal space are indicators of how the two people view their relationship. There is an intimate zone that is reserved for lovers, children, and close family members. There is another intermediary zone that is used for conversations with friends, to chat with associates, and in group discussions. There is a further zone that is used by strangers and acquaintances, and finally, a zone that is used for public speeches, lectures, and performances.
The size of one's sense of personal space is culturally determined, in addition to being dependent upon the nuanced relationship of the two interlocutors. Averaged estimates place one's sense of personal space at two feet on either side, 28 inches in front, and 16 inches behind for an average Westerner. Those living in densely populated places tend to have a smaller sense of personal space. Moreover, individual sense of space has changed historically as the notions of boundaries between public and private spaces have evolved over time.
Senses of personal space are intimately tied to the relationship between the two individuals involved. Entering someone's personal space is normally seen as an indication of familiarity. However, in modern society, particularly in crowded urban communities, it is sometimes difficult to maintain personal space; for example, in a crowded train. Many people find such physical proximity to be psychologically uncomfortable, but it is accepted as a fact of modern life. Sociologists study personal space precisely because of social implications of distance in regard to relationships.