Left-aligned text lines up at the left margin and is uneven (called ragged) at the right margin. Use left alignment for most documents, essays, reports, letters, and e-mails.

Right-aligned text lines up at the right margin, with an uneven (ragged) left margin. Right alignment is useful for page headers and numbers, for numbers in cells in tables, or for dates in a résumé. Avoid right-aligned text for large blocks of text.

Centered text aligns words at the center of the page, with uneven (ragged) left and right margins. Centered text can make titles and headings stand out from the rest of the text in a document. Centered text is also useful for flyers, invitations, and announcements. Use it sparingly as it has lower readability.

Justified text is aligned at both the left and the right margins, as on typeset pages in most books. Using the justify setting on a computer can add distracting gaps, or rivers, between words and can make passages hard to read. It is usually best to avoid the justify setting.