title: How does browser know the content type when such header is not specified?
body: <p>if the server doesn't send the content-type header, how does the browser tell which kind of content he got? For example, when I get the <a href="http://sstatic.net/so/img/logo.png" rel="nofollow noreferrer">SO logo</a> with chrome, the image is intact, though the server doesn't state its extension (at least, explicitly)</p>