The entire purpose of networking is to get traffic from point A to point B. When a computer requests information from another, packets are routed to the destination and then back. Sometimes, computers need a little guidance on how to get packets to the destination. This is known as routing. To assist with this, nodes utilize the concept of a routing table to help decide where packets should be sent given specific destinations. It would be very easy if every network in existence used the same IP scheme, but in truth, every network is completely different. To talk to a different network, your computer must know how to get to that network. Think of a routing table as a map of external destinations and the gateways to get to those destinations.

To better understand this, let's also talk about the concept of the default gateway. Typically, the default gateway is a router that understands how to talk to other networks. When you send a request for information over a network...