The supergalactic plane is a sheet-like structure that contains the Local Supercluster, the Coma Supercluster, the Pisces-Cetus Supercluster, and the Shapley Concentration, and that separates two giant voids – the Northern and the Southern Local Supervoids.

The supergalactic plane is the reference plane for the system of supergalactic coordinates, denoted by SGL (latitude) and SGB (longitude), analogous to galactic latitude (l°) and galactic longitude (b°). The zero point of supergalactic latitude and longitude is set at RA 2h 49m 14s, Dec +59° 31' 42", and the supergalactic north pole is at RA 18h 55m 01s, Dec +15° 42' 32", (epoch 2000 coordinates). The 0 point for SGL is the intersection of the supergalactic plane and the galactic plane.