A plan for reaching an end across many moves. Strategy chooses which battles matter; tactics fight them.
Greek στρατηγός (strategos, an army-leader, a general), from στρατός (stratos, an army) + ἄγειν (agein, to lead); a strategy was first the general's own plan for a whole campaign, not any single battle in it.
A plan reaching an end across many moves, choosing which battles matter rather than fighting any one of them. Strategy decides; tactics carry the decision out.