Services Question?

In Computer Management (in either w2k or NT), what is the basic difference between having a Service, say “pcAnywhere Host Service”, started and it can be “manual” or “automatic’?
In other words, does “automatic” mean the sevice will start automatically, when the PC re-boots? If it’s set to “manual” you will have to start the service each time (after a re-boot)?
Can someone give me an example of how to set a “start parameter”? I guess it is related.
Thx in advance…