A dual SIM router is a networking device that allows you to connect to the internet using cellular data through two SIM cards simultaneously. It's similar to a regular router but equipped with slots for two SIM cards, enabling redundancy and load balancing. This means you can use two different cellular networks for internet access, improving reliability and potentially increasing speed by combining the bandwidth of both networks. Dual SIM routers are often used in locations where wired internet connections are not available or as a backup solution for maintaining internet connectivity in case one network fails.