Folders on Server? How do they do this?

[Webskater]

Sorry, bit off topic but this is something I have never understood ... I have developed a lot of database driven web sites over the last 14 years or so - and, if I develop, for example, a web site to show properties and someone clicks on a property - the page address might look like ... www.propertysite.com/Propertydetails.aspx?PropertyID=168 ... and I'll fetch details of whatever property is wanted and show it on one page.

Then I look at the properties of a site like this (to see what it is developed in - i.e. what the page file suffix is)

http://www.realtor.com/realestateand...9_M45605-41980

and I think 'how do they do that? I mean, they can't create a folder for every property can they?

What mechanism is at work here?