How does a multiport repeater/hub function on a network? What are some of the roles of a multiport repeater/hub? What are some drawbacks of using these devices?

How does a network switch function on a network? What are some of the roles of a network switch? What are some advantages of using a network switch on a network instead of a multiport repeater/hub?

How does a network router function on a network? What are some of the roles of a network router? How are network switches and routers different?