It's called bbcode. bbcode is not standard and may be preceded by other letters, eg. ubbcode for the ubb board system.

It is not html but html is produced from it for the page output, eg. your link.

There are a couple of reasons I can think of for using it.

1. The code can be simplified and made easier for users.

2. A difficulty with html is if we just take it from an input form and pass it back it back in the post is that it all works. Some things that could be entered might not be desirable, others quite dangerous.


The bbcode way would only convert a tightly defined set of codes into html for the page. This might be seen by some as safer than effectively disabling or filtering out unwanted html.