Bows are an important element in play and ritualized aggression.  They are a form of metasignal with which dogs signal that they are “still just playing” even though, moments before they might have done something that could have appeared to be the initiation of a fight.

28 Day-Old Puppy Does a Play Bow

  16 Month-Old Adolescent Dog Does a Play Bow to Initiate Play with a Buddy