The default structure of a permalink uses the post ID as a unique identifier in the url: http://example.com/?p=1

To change the default URL structure (permalink) to something thats a bit more friendlier and more readable, go to Settings > Permalinks.

Permalink Tags

If you’ve chosen to use a Custom Structure then there are some useful tags available:

%postname% – post slug (post title)
%category% – category slug of where the post is stored
%author% – author name

You can use these tags to customize your permalink. Here are some good examples of common, custom, permalink structures:

/%category%/%postname% – yoursite.com/category/post-title
/%author%/%postname% – yoursite.com/miketylor/post-title
/%year%/%postname% – yoursite.com/2010/post-title