tabs and tab stops
For horizontal space in the middle of a line
On typewriters, the tab key moved the carriage to a fixed horizontal position, marked with a tab stop. This allowed typists to create columns of text or numbers, also known as tabular layouts (hence the name tab).
Tabs and tab stops still work the same way. A tab stop marks a location; typing a tab moves the cursor to that location.
These days, the tab is used only for inserting horizontal space in the middle of a line. If you need horizontal space at the beginning of a paragraph, adjust the first-line indent. For a true tabular layout, use a table, not tabs.
The tab is not as vital as it once was, but word processors still shortchange its capabilities. A new word-processing document has default tab stops every half inch. These default tab stops exist so that something happens when you type a tab in the new document. But this default behavior also suggests that what the tab key does is move the cursor a half inch at a time. Not true.
To get the most out of tabs, you should set your own tab stops. Avoid relying on the default tab stops—they undermine the goals of control and predictability. As with word spaces, also avoid using sequences of tabs to move the cursor around the screen.