In algebraic geometry, a cone is a generalization of a vector bundle. Specifically, given a scheme X, the relative Spec of a quasi-coherent graded OX-algebra R is called the cone or affine cone of R. Similarly, the relative Proj is called the projective cone of C or R. Note: The cone comes with the -action due to the grading of R; this action is a part of the data of a cone (whence the terminology).