I am not trying to be naive or an idiot, but I am a hobby C and OpenGL programmer, and I am just dipping my toes into client-server-based games. I'm learning about stuff not to necessarily implement it, but just to "learn my way around." My question is, in a game (3D) where there are 10 characters with "hit boxes" as skeletons, constantly updating these boxes to the server and client, how much bandwidth would that take (rough guess)? These are some more details:

1. Hit boxes are pyramids.
2. Hit boxes are described by 17 bytes.
3. There are a total of 340 bytes requiring transmit approx.

You forgot to say how often do you have to transmit the data, e.g. 30 FPS is not the same as 60 FPS.

EDIT: also to how many users (well, for how many users you're designing for, the usual amount you expect to be playing in a netgame, not the actual cap). That matters too.

Typically, the way that characters move is defined by some simple input, such as "which animation state is the character in" and "how far into the animation is the character." Or even just "what was the previous state of the character, and what was the user input," which lets you simulate everything based on initial game state and user input (the "lock-step" method.)