Punctuality is the characteristic of being able to complete a required task or fulfill an obligation before or at a previously designated time. "Punctual" is often used synonymously with "on time". It is a common misconception that punctual can also, when talking about grammar, mean "to be accurate".According to each culture, there is often an understanding about what is considered an acceptable degree of punctuality. Usually, a small amount of lateness is acceptable; this is commonly about ten or fifteen minutes in Western cultures, but this is not the case in such instances as doctor's appointments or school lessons. In some cultures, such as Japanese society, and settings, such as military ones, expectations may be much stricter.Some cultures have an unspoken understanding that actual deadlines are different from stated deadlines; for example, it may be understood in a particular culture that people will turn up an hour later than advertised. In this case, since everyone understands that a 9 am meeting will actually start at around 10 am, no-one is inconvenienced when everyone arrives at 10 am.In cultures which value punctuality, being late is seen as disrespectful of others' time and may be considered insulting. In such cases, punctuality may be enforced by social penalties, for example by excluding low-status latecomers from meetings entirely. Such considerations can lead on to considering the value of punctuality in econometrics and to considering the effects of non-punctuality on others in queueing theory.