There are many types of infrastructure routers available. In fact, Cisco routers are designed to address the needs of:

The focus of CCNA certification is on the branch family of routers. The figure displays the Cisco 1900, 2900, and 3900 ISR G2 family of routers.

Regardless of their function, size or complexity, all router models are essentially computers. Just like computers, tablets, and smart devices, routers also require:

A router also has special memory that includes Flash and nonvolatile random-access memory (NVRAM).