When two people talk, they often stand some distance apart. Each person has a boundary around their body into which other people may not come, thought we can't see it. If someone comes into his boundary people will move away to make the distance between them larger. So that means we only stand close to our good friends.
The interesting thing is that different cultures have different ideas about personal space. Usually, Americans like to have lager personal space than people from other cultures. So if you try to get too close to an American during your conversation, he or she will feel that you are "in his or her face” and will try to move away. So if the person to whom you are speaking moves away a little, don't try to go closer.
Also, try not to have body contact like holding hand with an acquaintance when you are speaking to them, since this may also make him or her feel uncomfortable. Shaking hands when you meet someone for the first time is OK, but this is only OK for that moment.
For most people who find personal space important for their safety, an unexpected contact can make them feel very uncomfortable. For example, if you were standing in an airport that was vacant and a person who you did know came up and stood very close to you, you would probably feel very scared.
Sometimes one’s need for personal space will change. Crowded places such as cinemas and sports grounds don’t leave room for people to enjoy personal space. But people often don’t mind not having personal space if they can have fun.
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