Tab stop

From an old typing / typewriter term that meant the mechanical carriage moved to the right by a certain distance when the tab key was pressed i.e. until it met the next mechanical 'tab stop'.

The purpose was to conveniently set out the spacing on a line. The typist pressed the tab key and the typewriter went to the right position for the next part of the line. The typist would set up the correct mechanical tab stops before starting a letter or memorandum.

Now that typewriters are rare the modern keyboard still has a 'tab' key that makes the cursor move by a 'tab spacing'.

In word processor applications you can still set out the tab spacing within a line as it helps speed up creating a document and producing a professional-looking document