URL structure determines what the addresses of individual pages look like. A good address is short, understandable even without opening the page, contains words instead of identifiers, and reflects the content's classification. It is recommended to use lower-case letters, hyphens instead of underscores, to leave out diacritics, and to avoid unnecessary folder levels. More fundamental than aesthetics is stability: an address, once published, should not be changed, because every change requires a redirect and some links get lost. For this reason, it is not recommended to put a date, a year, or elements that will stop being valid over time, into the address. On e-shops, a common mistake is including the product's category in the address, which makes it impossible to later move the product to a different category without changing the address. When preparing a new website, it therefore pays to design the addresses before the design itself, because the whole information architecture follows from them.
See also: URL parameters, 301 and 302 redirects, Information architecture.
