It's because of collision and broadcast domains. Routers allow to break both.
Nonroutable.
Protocols are set of standards that help programmers/designers/administrators to have common set of standards for Computing & Network Devices.
These are called protocols - a standard set of rules for common communications across networks.
Protocols
Connections between devices Devices
network diagram
A Linsky wireless router has become one of the standard routers used for DSL and home networking services. This is because they are inexpensive, easy to setup, and very reliable. Newer models offer different wireless protocols, as well the ability to establish connections with non-traditional devices. One of the peculiarities with a Linsky wireless router, however, is the tendency for the internal memory to become temporarily corrupted, requiring the router to be powered down and then restarted.
fire wire
The system can support 4 devices.
typically IEEE 802.11b or its other flavor a, g, etc.) Some short distance versions use BLUETOOTH
A protocol is a set of rules describing some behavior. In order to communicate in a common manner, the sender and receiver have to agree on the "language" of communication. A protocol states what those rules are, and because they are a standard, everyone agrees and knows what to expect.
You should be able to. The protocols used by these devices are standardized.