[TheDong]

The main draw is that you don't have to move your entire hand / the mouse along a surface.

That means your wrist sees less strain + motion, and you have no need for a mouse-pad, to name two possible benefits. Some people find it to be more precise as well, but I don't know if there's any evidence apart from personal preference.

Of course, your wrist still moves some as you manipulate the ball with your fingers, and if you use a trackpad you already don't need a mousepad-like-surface.

[pmarin]

> Some people find it to be more precise as well, but I don't know if there's any evidence apart from personal preference.

On CAD applications is very annoying when the mouse unintentionally register a movement while clicking a button which never happens with a trackball.

[dbcurtis]

> Some people find it to be more precise as well, but I don't know if there's any evidence apart from personal preference.

Well, for me it is much more precise. Or at least seems more natural.

But... ergonomic warning... I switch up between three different trackballs to keep “trackball thumb” from setting in. I get pain in the base joint if I don’t vary the angle, and also spend some time using a finger-positioned trackball.

[2muchcoffeeman]

It also takes up much less space and you can use a trackball anywhere because you don't need a surface.