A
graph search
algorithm. A* is guaranteed to
find a minimal solution path before any other solution paths,
if a solution exists, in other words, it is an "
admissible"
search algorithm. Each path is assigned a value based on the
cost of the path (e.g. its length) and an (under)estimate of
the cost of completing the path, i.e. the cost of a path from
the end of the current path to a solution.