The document discusses variable neighborhood search (VNS), a metaheuristic technique for solving optimization problems. It provides background on VNS, explaining that it was proposed in 1997 and explores predefined neighborhoods to escape local optima. The main concepts of VNS are described as involving shaking to move to a new neighborhood, local search to improve solutions, and moving to another neighborhood if no improvement is found. An algorithm is presented showing the process of defining neighborhoods, generating initial solutions, applying local search, and moving to new neighborhoods iteratively until a termination criteria is met. A variety of applications where VNS has been used are listed, such as scheduling, vehicle routing, and network design problems.