We support simple HTML, basic tags from BBCODE and of course Markdown (which is easiest to learn and use). Checkout documentation to Markdown:
BBCODE tags are limited to basic ones. We don’t allow changing font families, font colors and sizes ([FONT=Book Antiqua][SIZE=4]), just basic formatting. Manipulated fonts make reading harder (unusable on mobile) and sometimes led to very aggressive formatting ., I like how clean our post view looks.
For indent I use quoting using >, or lists using *.
You can still create nice looking and well formed article using Markdown. For example here.