This is SO's css path http://sstatic.net/so/all.css?v=6184" what is this ?v=6184"?

css

Solution

It's a way to control caching. When the value of the "v" parameter changes, the browser will consider it a different URL and ask for a new copy of the file instead of using its cached copy. This technique is often used to "version" static files by providing something like a timestamp in the query string that marks when the file was last changed.

Problem

Original source