A search method for choosing actions through many pretend tries.
MCTS is like a chess player with a tiny movie studio. It films many pretend games, then picks the move with the best endings.
It helps AI plan many steps ahead. You see it in game AI and tough choice problems.
Graph Search
MCTS is Graph Search on a tree of possible moves.
Heuristic Search
Heuristic Search uses quick guesses, but MCTS uses many pretend tries.
RL
MCTS can give RL stronger action choices and better planning.
MDP
MCTS can help an MDP find better action paths.