How to make phpstorm display line numbers by default?

Settings (or Preferences if you are on Mac) | Editor | General | Appearance and check Show line numbers.

Just now found where is it on Windows. Its View -> Active Editor -> Show Line Numbers (changes only for current document) and File -> Settings -> Editor -> Appearance -> Show Line Numbers (for all documents)

For Mac Version go to PhpStorm -> Preferences in menu. In the preference window go to IDE settings -> Editor -> Appearance -> Show Line Numbers (To change setting for all documents)

OR if you want to quickly set show line number PER CURRENT WINDOW even easier - right click on the long white column (where breakpoints are set) then select Show Line Numbers.

Red dot on the screenshot is a place where you have to click