That was the origin, but for everyday typing of non-tabular work, like letters, it was used for indenting paragraphs and address and signature blocks. And it al

That was the origin, but for everyday typing of non-tabular work, like letters, it was used for indenting paragraphs and address and signature blocks. And it always moved to the next tab stop to the right on the line. ASCII calls it HT, ‘Horizontal Tabulation’. Later, some systems, notably IBM's, overloaded this to move to the ‘next’ field on a form, which might be to the left and down the page. So from there MS-DOS/Windows stuck us with a Tab that sometimes moves horizontally within a text field, and sometimes moves to a different field. Just like Return sometimes moves to a new line/paragraph and sometimes submits a form.