Official formats and tournament play have been an integral part of
Magic since its inception, ranging from casual-level events such as
FNM and
Prereleases to the professional-level
Pro Tour and
World Championships. Organized play is formally headed by the
DCI, which provides game rules, tournament operating procedures, and other materials to private tournament organizers and players through the
Wizards Play Network; it also used to operate a
judge certification program to provide consistent rules enforcement and promote fair play. The
Judge Wiki is probably the best place to look if one wants to get more involved with judging.