Special characters like (, <, ' ' (space) and é are 'escaped' before passing as an URL parameter (what follows after the ? in an URL like search.php?text=risqu%C3%A9 ). For an overview of all the special characters in HTML, see the HTML character map.
search.php?text=risqu%C3%A9
For developers:
Server.URLEncode(Text)
HttpServerUtility.UrlEncode(Text)
encodeURI(Text)
URLEncoder.encode(Text)
urlencode($text)
url_encode($text)
urllib.quote_plus(text)
CGI.escape(string)