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Backtracking is a general problem-solving algorithm that involves iteratively searching for a solution to a problem by exploring all possible __. It is especially useful when the problem has multiple valid solutions, and the goal is to find one or more of these solutions.

The idea behind backtracking is to build a solution incrementally by selecting candidates one by one and then evaluating if the current candidate leads to a valid solution. If the current candidate does not satisfy the problem constraints, the algorithm backtracks to the previous step and tries a different __.

Backtracking can be visualized as exploring a ____ search space, where each level of the tree represents a step closer to the final solution. The algorithm explores all possible paths in the search space until it finds a valid solution or exhausts all possible candidates.

Backtracking can be a powerful technique for solving a variety of problems, such as finding combinations, permutations, or solving puzzles like Sudoku or the N-Queens problem.

Let's take a look at an example of an N-Queens problem solved using backtracking in C++: