HEALPix is a Hierarchical, Equal Area, and iso-Latitude Pixelation of the sphere designed to support efficiently (1) local operations on the pixel set, (2) a hierarchical tree structure for multi-resolution applications, and (3) the global Fast Spherical Harmonic transform. HEALPix based mathematical software meets the challenges presented by high resolution and large volume data sets, such as the WMAP and Planck CMB mission products.