refers to a graph search strategy that considers states in a graph recursively. So, If the present state is not the goal state, then its first child (node) is examined. If this child does not represent the goal state, then its first child is taken. If there are no children of a state, then the next sibling of the present state is considered. If there are no further siblings of a state, then the sibling of the state
BACKTRACK SEARCH: "A backtrack search aims to find a goal state by moving back through a series of nodes."