The indent guide makes your code's readability much better. What is an indent guide? Suppose you have a html DIV start and closing tag. That div tag has a lot of children div tags. Sometimes its impossible to detect the start and closing div from these. The indent guide can help you in these cases. I am going to tell you how to apply it on atom code editor.
Without indent: 
With indent:
To get that on your atom editor go to the Atom Edit > Preferences > Editor or you can use keyboard shortcut Ctrl + ,
There you will find the Show indent guide and show invisible check-boxes. Check them. You are done. The show invisible will show the hidden spaces and tabs.
Happy Coding!