Informal names are awarded at birth and may continue in use to the extent one may have to check the formal registration to find a person's given formal name. Thais typically address one other by nicknames (; ). Bestowed by relatives or playmates in early childhood, these are commonly one syllable (or worn down from two to one). These may often be nonsense words or humorous and seldom relate to the registered name except in cases where it is a diminutive, such as "Nok" for "Noknoi", or 'bird' from 'little bird'. All Thais have such names; they are freely used in everyday life. Some may have additional nicknames bestowed by friends or colleagues, especially during school or adolescence. Nicknames may link with a notable physical feature or behavior. In everyday life, a Thai is introduced by nickname and others may not know the person's formal name. When so introduced, one usually continues to use the nickname.