Repeater- when a network signal needs to travel over long distances, the signal will weaken the further it travels. A repeater will receive the signal and boost the strength of the signal and send it to its destination. A repeater is defined as a layer one device. repeaters are used for both wired connections, as well as wireless.
Router- A router directs network traffic to the receiving IP address. Routers are common in households with an internet connection, as most internet providers install a modem and possibly provide a router is needed. Routers provide network security with WPA2 password protection. Some models of routers offer wireless capabilities as well. Routers let multiple devices use the same internet connection by assigning local IP addresses. A router is defined as a layer three device.
Switch- A common term used in networking that I have trouble to get a full understanding, as I do not work professionally in IT. A switch from what I understand is a device that receives and forwards data by mac address rather than IP addresses. Going by mac address allows for faster data transfer over local networks and is a lower tiered device at level two.