  This document presents HiPS, a hierarchical scheme for the description,
storage and access of sky survey data. The system is based on hierarchical
tiling of sky regions at finer and finer spatial resolution which facilitates a
progressive view of a survey, and supports multi-resolution zooming and
panning. HiPS uses the HEALPix tessellation of the sky as the basis for the
scheme and is implemented as a simple file structure with a direct indexing
scheme that leads to practical implementations.
