A reinforcement learning algorithm that updates value using the action it actually takes.
SARSA is a driving instructor with a dashcam. If you turn into the taco drive-through, it grades that trip.
Robots and game bots use it. It learns by trying the current plan in real runs.
RL
SARSA is a classic RL method for learning an action plan.
TD Learning
SARSA uses TD Learning to update value from the next step.
On-Policy Learning
SARSA learns from the action its current policy really takes.
Q-Learning
SARSA learns the real route, and Q-Learning learns the best-looking route.