elements of a game
Before you can analyze any strategic situation, you have to write it down in a clear, shared language — the same way a board game comes with a rulebook telling you who plays, what they may do, and how someone wins. In game theory that rulebook has three core parts: the players, the strategies, and the payoffs. Naming these three things turns a vague conflict ('we're competing') into a precise object you can actually reason about.
The players are the decision-makers — two coffee shops, a buyer and a seller, two nations. The strategies are the complete set of moves available to each player; for one firm that might be just 'high price' or 'low price', for a chess player it is far richer. The payoffs are the numerical reward each player receives for every possible combination of moves — usually profit, utility, or some measure of how happy that outcome makes them. A fourth ingredient often matters too: information — who knows what, and when (do players move at the same time, or in sequence; can they see each other's choices?).
These elements are not bookkeeping; they decide everything. Change the payoffs and a friendly game can turn cutthroat; change the information (say, let players see each other's moves) and a one-shot standoff can become a negotiation. Setting up the elements correctly is the hardest and most important step in any real application — get the players, options, or rewards wrong, and the cleverest mathematics afterward will answer the wrong question.
Rock-paper-scissors written as a game: players = two kids; strategies = {rock, paper, scissors} for each; payoffs = +1 to the winner, -1 to the loser, 0 each on a tie; information = both move at the same time, blind to the other's choice. With those four lines fixed, the whole game is fully specified.
Rock-paper-scissors broken into players, strategies, payoffs, and information.
Most real-world disputes about a game theory model are really disputes about its elements — usually whether the payoffs or the information were specified correctly, not the math that follows.