Why do humans like being touched?
Of all the senses, touch is the one that most connects a person to the external environment. When two people touch each other (a handshake, a hug, a kiss, etc.) a connection/bond is made. This bonding is deeply involved with social development and emotional interaction.

Interpersonal relationships are essential for social interactions. It is important to known where the boundaries are in your culture, so that personal space is respected. This varies widely between cultures and persons.