A double attack is a tactic that threatens two of the opponent’s targets simultaneously with a single move, forcing them to choose which one to save.
The logic is straightforward: a player can only make one move per turn. If two pieces or weak points are threatened at the same time, only one can be defended — the other falls. The double attack takes several forms: a fork (one piece attacks two targets), a discovered attack (a piece moves and uncovers an attack from a piece behind it), or a double check (two pieces give check at the same time). A classic example: a knight landing on e5 that simultaneously threatens the opponent’s queen on g6 and an undefended bishop on c4.
In practice, look for positions where two enemy pieces are poorly coordinated or left undefended. Before each move, ask yourself: "Does this move create two threats at once?" Even a secondary threat forces a response and hands you the initiative.