What does the Stop Workflow and log... action do?

I have used the stop workflow action in my SPD workflows but it doesn't seem to do what I thought it would.  It doesn't stop....it goes right on to the next step!

I want to be able to say if a condition is true, stop the workflow, do not go any further, quit!
If the condition is false, then go on to the next action or step.

How do I get a workflow to completely stop even if there are more steps!


Tearing hair out,
Judy