The about URI Scheme took me a lot of google-fu. It’s that chrome:// text that pops up in Chrome browser address bar. I would not have found what is it called if I has not asked in my team’s group chat. A kind colleague that happens to have some ties to Wikipedia manage to find this article.

What is the about URI Scheme?

• The about URI scheme is an agreed schema implemented by all web browsers. It reveals the internal state of the browser and some of its built-in functions.
• To find all its commands, enter about:about into your web address bar. Take note that it has to be the address bar!
• Different browsers have about URI Scheme. For example, you may find about:history in Chrome but you won’t find it in Firefox (at this point of writing). However, there are a few common ones, like about:about.