The Standard Aside Or Aside From The Standard

What is this all about in WordPress.com with the different kinds of format for posts?

This is what the WP support page says about the formats:

Standard – Your normal, average, everyday blog post. This is the default styling for your theme.
Gallery – Usually will show a thumbnail from the blog post, as well as an excerpt of what the gallery is about.
Aside – These are brief snippets of text that aren’t quite whole blog posts. Useful for quick thoughts and anecdote

I am going to mark this post as an ‘Aside’ and let’s see what it looks like.

Postscript
Having seen the post I now see that the whole of the post is laid within a yellow box. Oh well.