wiki sez:
HTML is written in the form of HTML elements consisting of tags, enclosed in angle brackets(like <html>), within the web page content. HTML tags normally come in pairs like <h1> and </h1>. The first tag in a pair is the start tag, the second tag is the end tag (they are also calledopening tags and closing tags).
http://en.wikipedia.org/wiki/HTML
thus, </thread> = closed thread