Sites that provide any URL mapping service, where a URL is mapped or "shortened" to a reference URL supplied by the service. This also includes the shortened URL itself. Note that these services may measure traffic to those links. Also, these are not proxy avoidance sites; the original URL is still requested by the browser.
Examples: tinyurl.com t.co youtu.be bit.ly ow.ly amzn.to 1drv.ms aka.ms x.co trib.al