In five seconds, you will be creating better-looking documents: Five, four, three, two --
Stop centering your text!
-- One. There, now your documents look better.
Centered text looks OK for some special uses, such as page titles or formal invitations, but not much else. Here's why:
Centering creates jagged line edges,
which can make a layout look messy, and
it makes the copy hard to read,
because the eye has to jump around so much
from line to line.
You see it all the time, but that doesn't make it right.
Centering text comes under the heading of "Just because you can do it, it doesn't mean you should."