When out with friends, colleagues or relatives, it is customary for people to take turns buying rounds of drinks: each person in turn pays for a a drink for everyone present.

The round is about much more than drinking. It is a complex social activity that keeps the peace. Dr Peter Marsh, co-director of the Social Issues Research Centre, says that below the surface the pub round is a complicated, highly regulated social ritual. "There's a lot of monitoring - because you don't want to buy the drinks too early, you don't want to buy them too late. There are unwritten rules, such as if half the round are towards the bottom of the glass, that's the time to buy."

The greatest social danger is to be labelled as a round dodger who can never find their wallet. On the surface everyone might be smiling, but they are keeping a close eye on the progress of the round. But people who buy too many rounds are equally unpopular, as this is seen as showing off.

Practically, the layout of a traditional pub would struggle if every customer bought an individual drink. It would clog up the pub, with too many people going backwards and forwards.

Finally, one shouldn't miss the significance of the giving and receiving within a group: "It's civilisation in action in a pub."

The etiquette surrounding this practice is as follows:

DON’T :
*offer money to the person buying a round,
*fail to take a turn at buying a round,
*refuse a drink (even if you know you will not stay long enough to buy a round, do accept it with thanks)
*stay clear of the practice entirely and just buy your own drinks

DO :
*request a drink of the same or relatively similar value as everybody
*go through the 'buying procedure' once, unless the session is sufficient in length that your turn comes back around
*have a bit of good-natured argument about who gets to (not "has to") buy the next round