Greedy Best-First Search is a pathfinding algorithm that focuses on exploring the most promising nodes first. It uses a heuristic function to estimate the cost from the current node to the goal, selecting the node with the lowest estimated cost for expansion. This approach aims to find a solution quickly by prioritizing paths that appear to lead most directly to the target. However, Greedy Best-First Search does not guarantee the shortest path, as it may overlook longer paths that could lead to a more optimal solution. It is often used in scenarios where speed is more critical than accuracy, such as in certain AI applications and game development.