Algebraic topology is generally the study of functors from nice categories of spaces to algebraic categories. This can be considered, from the nPOV, as closely related to higher category theory. Category theory originally developed out of algebraic topology, where it was used first simply to describe what was going on and then to axiomatise Eilenberg-Steenrod cohomology theories. There has been considerable convergence of the two subjects, not only in methodology, but in aims and motivations.