The biggest problem on the mobile site (not app) for any Stack Exchange website is there are no formatting tools at all. This makes asking and answering far more difficult since I have to use the 'full site' option, which is very inconvenient on a 5.2" screen. I am hoping a developer reads this message and adds formatting for mobile-reliant users like me.
I usually don't need or use the formatting buttons, except in cases such as putting a huge amount of text into a code block.
Psst! It's a secret! They're basically just shortcuts!
The B and I buttons just put one or two asterisks around the selected text, which the server parses into bold and italic. *One star* makes italic, and **two stars** makes bold. `backticks` can create
code spans as well. You don't even need these either, because the HTML
<code> tags are whitelisted and can be