[itistricky]

The link is weird. What is :99 at the end of it?

[speedgoose]

Probably the identifier of the article. A long time ago, we used to use auto-incremented positive integers straight from the database instead of UUID or adjective-adjective-noun.

[alexjurkiewicz]

It's part of the URL path.

schema: http, domain: hintjens.com, url path: /blog:99

It looks a bit like a port number, but it's in the wrong place. For that you'd want http://hintjens.com:99/blog