The three elements of Command and Control (C2) command authority are operational control (OPCON), tactical control (TACON) and administrative control (ADCON).
OPCON
OPCON is the level of C2 command authority that PERFORMS FUNCTIONS OF COMMAND OVER SUBORDINATE FORCES, and is accomplished by commanders at any level at or below the combatant command. OPCON involves organizing and employing commands and forces, assigning tasks, designating objectives and giving authoritative direction to accomplish a task.
TACON
TACON is the level of C2 command authority that PROVIDES DETAILED DIRECTION AND CONTROL OF MOVEMENTS OR MANEUVERS within an operational area to accomplish the mission or task, and is accomplished on any level at or below the combatant command. TACON involves controlling and directing the application of force or tactical use of combat support assets within the assigned mission or task.
ADCON
ADCON is the level of C2 command authority that EXERCISES AUTHORITY FOR ADMINISTRATION AND SUPPORT. ADCON involves organizing of service forces; controlling of resources, equipment and unit logistics; personnel management; individual unit training; and readiness, mobilization, demobilization and discipline.