High Quality Content by WIKIPEDIA articles! In algebraic topology, a branch of mathematics, the Steenrod algebra is a structure occurring in the theory of cohomology operations. It is an object of great importance, most especially to homotopy theorists. More precisely, for a given prime number p, it is a graded algebra over the field Z/p, the integers modulo p. Briefly, it is the algebra of all stable cohomology operations for mod p singular cohomology. It is generated by the Steenrod reduced pth powers, or Steenrod squares if p=2. The requirements of calculations of homotopy groups mean that homological algebra over the Steenrod algebra must be considered.