PLC Switch Types

I've been following a few tutorials on learning PLC, using namely LogixPro. I noticed on this particular piece of software (and tutorials) they reference different types of switches. I understand how to change the switch type, but I'm unfamiliar with the names or lingo of the different types.

As an example they say:
N.O. pushbuttons
N.C. Stop switch

I was curious if there was any kind of diagram or basic explanation anywhere for the different types of switches so I don't get confused to which type I should be using.

Thanks in advance.

http://www.patchn.com/symbols.htm good source!

PushButtons are momentary contact switches, the switching is active only while the pushbutton is depressed.

E-stops are typically push-pull maintained contact switches, once the switch is pushed, the switching will be maintained, until it is switched back by pulling on the mushroom head.

Toggle switches, rocker switches and the standard light switch are all maintained switches, the horn in your car is a momentary.

See this link: http://news.thomasnet.com/IMT/archives/2002/07/electrical_swit.html?t=archive

Thanks! Exactly what I wanted to know.