Why is it that a vector can be described in terms of a simple linear combination, like v = xi + yj + zk, where v is a vector, and i, j, and k are all unit vectors. It just seems a bit convenient that it's as simple as just adding the components this way. It seems like there should be a bit more to it. I guess I'm just looking to get as fundamental with the concept as possible. Is it just a matter of this being the definition of a vector by convention?