No worries at all, people tend to get confused when they hear "skinning", don't think about actual skin at this point, think of "skinning" as the process of assigning which vertices you want maya to manipulate when a specific joint is being moved.
To blow your mind a bit more, I have had to use "skinning" for props, vehicles and even an environment! Its simply the fact of helping Maya understand which vertices you want a joint to be assigned to pretty much.
With that said, a robot huh? I highly recommend using joints and skinning it to the entire geometry. I wouldn't go about simply doing parent to child relationships, for the simple fact whenever you want to animate the legs it will be a huge hassle, since legs tend to use IK, which stands for "inverse kinematics", IK is used basically to only manipulate 1 single controller to move the leg, rather than animating the "thigh controller" and "knee controller" for example.
Where do you pace your joints for your character though since its a robot?? A pretty cool tip is this... the placements of your joints will depend on where you want a character to be deformed. For example lets say an arm, has a shoulder, elbow and wrist joint. You know where your elbow rotates from for example, you wouldn't want to place your characters elbow joint on his forearm, why? well because the deformation will look improper.
I see you are also worried by moving your elbow joint that you might be moving other joints you don't want like a leg joint for example. No need to worry at all about that! See, joints have parent to child relationships, each one has its own root joint, for example again.. an elbow's root joint is the shoulder. An ankle's root joint is the thigh. The head's root joint is the neck, and all of those root joints have a MAIN root joint which comes from the hip, the center of gravity. This is your main root joint in which once you move, all your joints follow since it is the parent.
Another thing to keep in mind, you will want controllers to manipulate your joints. Never ever send a rig to an animator expecting them to animate from the joints themselves, that is not proper studio pipeline procedure.
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