Probably all programming languages use some kind of indentation formatting scheme. It's usually not required, although exceptions exist (Python, YAML) where proper indentation rules are enforced. Amy tries to ease the task of formatting your code by smart indentation. It varies from language to language, indentation is (as many other rules) defined in the language grammar contained in a bundle.

If you need to manually adjust indentation of a block of text, you can use Command+] (Ctrl+]) for indenting to the right, and Command+[ (Ctrl+[) for indenting to the left. If you have lines selected, the selection will move all. If you don't, the indentation applies to the active line (where caret is). In the latter case, caret doesn't have to be on the left (beginning of the line).