If this checkbox is selected, tab characters are used:
On pressing the Tab key
For code reformatting
When the checkbox is cleared, PhpStorm uses spaces instead of tabs.
If this checkbox is selected, the part of indentation defined by the nesting of code blocks, is made of the tabs and (if necessary) spaces, while the part of indentation defined by the alignment is made only of spaces.
If this checkbox is cleared, only tabs are used. This means that a group of spaces that fits the specified tab size is automatically replaced with a tab, which may result in breaking fine alignment.
The Smart Tabs checkbox is available if the Use Tab Character checkbox is selected.
In this text box, specify the number of spaces included in a tab.
In this text box, specify the number of spaces (or tabs if the Use Tab Character checkbox is selected) to be inserted for each indent level.