As Maria said, is a normal way in Brazil, but normally isn't a kiss with "loud". Normally the people touch their faces and simulate a kiss or give a very fast kiss. Is not useful betwen males.

It is also part of our greetings. It is the usual way in Brazil, as Tito said among women and men facing women. Men don't kiss their friends. In some professional occasions, it is not the way people greet either. But, in general it is a personal choice. Everybody can do what makes him/her feel good.

yes, it is, among girls or males facing females, at the beginning, when they meet, and to "say" bye bye. Even on formal ocasions, well,it is in portugal, in some countries, even in europe is also usual among males. well, we dont need to touch, ehehe. is a interesting question, to check how it is diferent among cultures, in muslims or arab countries is usual, for exemple, touch each others, even males. Well, there is a good author who speaks about it, E. Hall, or even paul ekman (emotions). bye dear, Na.