Many Americans find silence uncomfortable during a buffet or a formal dinner. So in the States there is a widespread practice of making "small talk" in certain social situations. Small talk deals with various topics superficially, simply for the sake of keeping a conversation going. The topics might include the weather, sports, college courses, clothing, food, etc. Small talk is especially useful at social gatherings when you meet someone for the first time, or when polite conversation is expected but no serious discussion is desired. It is common but not necessarily expected that one knows someone in a group before engaging with him or her in conversation. However, at a party or other informal social gathering, a simple "May I join you？" and a self-introduction is normally sufficient to gain acceptance into a group and to join in a conversation. In some places, such as the lobby of a concert hall or theater, a waiting room or a classroom, it is common for strangers to start a conversation even without an introduction.