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.