Search is the systematic examination of states to find path from the start/root state to the goal state.
The set of possible states, together with operators defining their connectivity constitute the search space.
The output of a search algorithm is a solution, that is, a path from the initial state to a state that satisfies the goal test.
In real life search usually results from a lack of knowledge. In AI too search is merely a offensive instrument with which to attack problems that we can't seem to solve any better way.
Search techniques fall into three groups: