r(t) : R→Rn=⟨x0(t),⋯,xn(t)⟩ is a vector(-valued) function. r is a parameterization A curve C is parameterized by r on an interval of t Properties dtdr(t)=dtd⟨x0(t),⋯,xn(t)⟩=⟨dtdx0(t),⋯,dtdxn(t)⟩