How do you decide what is and what isn't part of your city?

To rephrase this question, which of various definitions that are used on this site do you feel most strongly defines the extents of, your city and also of any city. There are various I see used, often by people who want to discuss population figures, but sometimes definitions arrived at by calucation and suchlike are used in other threads. So I don't mean where would you draw the line for population measurement, but where would you draw it in ordinary conversation.

And example about metro figures, I see that in the US they are very clearly defined and well known, whereas in the UK not many people are aware of this sort of technical metro area and where they are used for discussion of something outside of population measures, such as saying which city a certain place is in, it can get confusing, as there are many places which are within one or more metro area. An example, say, Warrington, a town between Liverpool and Manchester, which would be in the metro area by US definitions (and is in the city region by UK definitions) of both. yet Warrington is large enough to have it's own culture and definition. Most people in the UK know where Warrington is as a seperate town and don't treat it like a suburb and no-one in Warrington has anything remotely like a Liverpool or Manchester accent, the two cities football teams aren't massively popular there, in fact Warrington is more of a rugby league town. Anyway, the point I make is Warrington is a distinct place. Yet in most of America cities stand as islands almost with their metro area a fuzzy boundary between the city and the country/desert but not so much confusion about the fact that places within the metro area definitely relate strongly with the city.

So which boundary of place means most to you? examples could be The metro area, the city proper, some historical boundary of the city, a ring road, the continuous urbanised area or some more cultural definition, such as the local accent.

I ask this because I'm interested in the culture of cities and the relationship of this culture to 21st century patterns of urbanisation which certainly don't keep to any boundaries of culture or anything like that.>