This article is from the Ergonomics and Typing Injury FAQ, by Dan Wallach firstname.lastname@example.org with numerous contributions by others.
Typing management tools aim to help you manage your keyboard use, by warning
you to take a break every so often. The better ones also include advice on
exercises, posture and workstation setup. A few use sound hardware to alert you
to a break, but the majority use beeps or screen messages.
Often, RSI appears only after many years of typing, and the pain has a delayed
action in the short term too: frequently you can be typing all day with little
problem and the pain gets worse in the evening. These tools act as an early
warning system: by listening to their warnings and taking breaks with
exercises, you don't have to wait for your body to give you a more serious and
painful warning - that is, getting RSI.