Social and informal settings allow people to communicate without any barriers and be more open about their thoughts and feelings.
While speaking to people (young and old), sending an email, or using the telephone, you have to refrain from using slang and always use professional and appropriate language. This is because you are now representing a company or organisation and so need to portray professionalism at all times.
Different cultures may use body language and gestures which are different to us. If for example someone avoids making eye contact with you, this could be due to a cultural difference. In some countries it is considered disrespectful to look into a senior persons eyes. Whereas in the UK, it is considered rude not to look someone in the eyes when speaking to them.