Think about it this way: If your car pulls out of your driveway, someone can follow you and see where you are going, how long you are at your destination, and when you are coming back. They might even be able to peek inside your car and learn more about you. With a VPN service, you are essentially driving into a closed parking garage, switching to a different car, and driving out, so that no one who was originally following you knows where you went.
As the size of the link state database increases, memory requirements and route computation times increase. To address this scaling problem, OSPF divides the network into areas (collections of contiguous networks) that are connected to each other through a backbone area. Each router only keeps a link state database for those areas that are connected to the router. Area border routers (ABRs) connect the backbone area to other areas.
Are you so used to your data traveling over Wi-Fi that you've stopped worrying about the security of that data—and about who else might be spying on it, or even stealing it for nefarious purposes? If so, you are—sadly—in the majority, and you ought to consider using a viritual private network, or VPN. In fact, when PCMag conducted a survey on VPN usage, we found that a dismal 71 percent of the 1,000 respondents had never used a VPN. Even among those who support net neutrality—who you might think would tend to be well informed on technology and privacy issues—only 45 percent had used a VPN.