Two types of networks are LANs (local area network) and WANs (wide area networks). Early WANs used circuit telephone lines for their connections. The combination of telephone lines and the closed switches that connect them to each other is called a circuit. The circuit follows a path from the caller to the receiver, and as the connected circuits switch to one another, it is called circuit switching. The problem with this was when one of the circuits failed to connect, the connection was interupted. To fix this problem, the Internet began to use packet switching networks. In this type of network, files and e-mails are broken down into smaller pieces called packets. They are labeled electronically with their labels, sequences, and destinations. These packets can all take different paths to the same destination, where that computer reassembles them into the original document and alerts the user to their arrival.
As these packets travel, the computers they are coming in contact with decide what the best paths are for the packet to take. These routing computers use routing algorithms to determine the best route. Individual LANs and WANs have different rules and standards for creatin packets in their network. Routers, hubs, and switches are the standard devices that can be used to transfer packets from network to network.
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