You probably know that there are several ways to align text: left-aligned or justified, for example. Justified text is not usually appropriate on the Web, and the other types of text have specific uses.
Types of text alignment
- Left-aligned or "flush left" text has a straight-line left margin, but a ragged right margin as different lines take up different amounts of space.
- Right-aligned "flush right" text is the reverse, lined up along the right margin instead.
- Justified text (used in newspapers) has word and letter spacing altered so that it lines up along both margins.
- Sometimes lines of text are also centered on the page.
Justification - why not?
People often want to use justified text on the Web because they think it looks "tidier". However, this is not often appropriate, and is more difficult to read than left-aligned text.
This is because of the low resolution of screen displays. Screen displays cannot cope well with the addition of small, subtle amounts of space between words or letters. As a result, justification always looks poor on screen displays. It tends to result in uneven spacing, and can also sometimes break up the shape of the word (we recognise words based on their overall shape, not on the individual letters).
Justification in printed publications also relies on hyphenation, which means that a word can be broken in two if it does not comfortably fit on one line. Current Web browsers do not support hyphenation, which means that justification results in more extreme changes in spacing.
Centered text is sometimes appropriate for headings. It is not a good choice for body text because it usually looks a bit ugly and is difficult to read.
Sometimes centered text can be okay for short, narrow paragraphs (two or three lines, each only five or six words wide).
Right-aligned text can be useful for effect in some cases, or as part of navigation (you might want to right-align all the options in a navigation menu).
Left-aligned text is best suited to almost all "body text" use on the Web.