title: dashes vs underscores in URL
body: <p>In URL rewriting, i am quite confused that should i use underscore <strong>(_)</strong> OR hyphen <strong>(-)</strong>  to replace spaces. According to <a href="http://haacked.com/archive/2007/03/15/dashes-vs-underscores-in-urls.aspx" rel="nofollow noreferrer"><strong>this</strong></a> and <a href="http://www.codinghorror.com/blog/2006/04/of-spaces-underscores-and-dashes.html" rel="nofollow noreferrer"><strong>this</strong></a>, hyphen should be used.
  But <a href="http://en.wikipedia.org/" rel="nofollow noreferrer"><strong>wikipedia</strong></a> uses underscores like en.wikipedia.org/wiki/Computer_network_programming. so which should be used?</p>