What Are Actuators

I have heard talk about them but never knew what they are, need some help...............please explain. Links would be helpfull :D

There are a few differnt types, basically they are push/pull rods that are controled by an electric motor.

There are a few differnt types, basically they are push/pull rods that are controled by an electric motor.

not always a motor, sometimes they are a solenoid.

Or vacuum, or hydrolic.

so what are these push/pull rods :S

they deliver motion on demand. want auto lambo doors? actuators can be correctly designed into the door to give the correct force at the correct angle to the pivot to open the door automatically after it has been unlatched. as one example.
as another you can use actuators to have a sliding amp rack or wrap around speakers such as on the Alpine show car.
actuators can be used along with memory circuts to remember seat configurations and move the seat to your likings automatically after someone else has driven your vehicle...