If you need to comment out multiple lines in Sublime Text 2 or 3, there’s a short keystroke that you can use. First, you need to highlight the block (multiple lines) that you want to comment out, then press Ctrl + /. You can press it again to toggle on and off.
Line 1 Line 2 Line 3
Pressing Ctrl + / will comment out the highlighted block.
#Line 1 #Line 2 #Line 3
Press Ctrl + / again to toggle it back.