YOURLS stands for Your Own URL Shortener It is a small set of PHP scripts that will allow you to run your own URL shortening service (a la TinyURL or Bitly)
Running your own URL shortener is fun, geeky and useful: you own your data and don't depend on third-party services It's also a great way to add branding to your short URLs, instead of using the same public URL shortener everyone uses
Keep up to date: read the official YOURLS Blog
You will also find numerous unofficial installation guides on Awesome YOURLS, a curated list of resources