Rip-up and reroute
Beginner
Pulling out a wire that is in the way and drawing it again somewhere else, so another wire can fit.
Novice
A repeat-until-done method: route every net, sometimes letting them overlap, then remove the nets involved in conflicts and route them again with the crowded spots made more expensive. Repeat until nothing conflicts.
Expert
It converges only if costs remember history; otherwise nets trade places forever. The rip-up order, the region rerouted (whole net or a local window) and the cost schedule decide convergence. Global routers use it as negotiated congestion; detailed routers as search and repair.