What is Backtracking?
Backtracking is an algorithmic-technique for solving problems recursively by trying to build a solution incrementally, one piece at a time, and abandons a candidate (or "backtracks") as soon as it determines that the candidate cannot possibly result in a valid solution.
Where is it used?
Usually in constraint satisfaction problems. Backtracking is useful while solving certain NP-complete problems where the theoretical upperbound is as bad as N! or 2 ^ N or even N ^ N.
