This article provides the basic concepts, complexity analysis, and discussions on the disjoint paths problem. The disjoint paths problem has a wide range of applications across various network types, particularly in providing a more reliable service to network traffic. Traffic that can make use of disjoint paths is more robust to the effect of network node or link failures. This article also covers many different variants of the disjoint paths problem, namely, the availability‐based disjoint paths problem, the maximally disjoint paths problem, the domain‐disjoint paths problem, the shared risk link group (SRLG)‐disjoint paths problem, the region‐disjoint paths problem, and the disjoint path pairs problem.