WiFi routers can be categorized by different types based on frequency bands, speed, range and other technical specifications. The most common types include single-band (frequency of only 2.4 GHz), dual-band (frequency of 2.4 GHz and 5 GHz), tri-band (one 2.4 GHz and two 5 GHz), and quad-band (frequency can be up to 6 GHz) routers.