What is a Mac Pro?

[CHMK]

Sorry, but can anyone tell me what a macpro really is used for?? is it just like a huge block of tech goodness that u can connect to a display monitor like a thunderbolt?
cos i know i mac is a monitor with the tech goodness built inside.

so are mac minis and mac pros just connected to any old monitor? havent really been able to find the answer.

and if so, can u actually connect a mac pro to say a macbook pro or an iMac? just really confused. i know its a workstation whatever that is so if someone could tell me in simple terms id be grateful. thanks!