Spatial zones are imaginary boundaries within which people interact. These zones are often referred to as various levels of personal space. The four zones are as follows:
Intimate Zone - skin on skin contact --> 18 inches away. The intimate zone is appropriately named as we share this zone with those that we are the closest to. This zone is typically associated with whispering and touching. This zone is typically shared with romantic partners or close friends - those who we feel we can be the most vulnerable with.
Personal Zone - 1.5 ft --> 4ft apart. This zone is comfortable with family and good friends. Those that we do not feel threatened by. As relationships develop in the workplace and employees get more comfortable with each other, this zone might be used. Within this zone, we typically choose to interact with those we feel we know and who know us well. Rarely would one spend an extended period of time interacting with a stranger or acquaintance in this zone.
Social Zone - 4ft --> 12ft apart. This zone is perfect for interacting with acquaintances. This zone provides enough distance to allow a feeling of security. We can see the entirety of the other person's body, there should be few surprises in these interactions for this reason and that makes us feel secure. If the person we're interacting with does end up being hostile we have the time and space to attempt escape. If the person is one that we bond with they could move into the personal zone.
Public Zone - 12ft - 25ft away. This zone is typically used for addressing crowds. One might use this zone during public speaking as in a lecture, when addressing guests at a party, etc. This is not an appropriate zone in which to have intimate conversation. This zone is typically reserved for professional roles or times when many people are looking to one for some sort of guidance.
Much can be learned by observing the zones people engage in with each other. You can infer current comfort level, people's roles and sometimes even the tone.