One area that is important to understand about networking is the two primary protocols that networked services can use: TCP and UDP. Services can listen on these ports using either of the protocol—and many a times do. TCP (frequently shown as TCP/IP) is used for connections that need things to be ordered specifically—for example, loading a web page. UDP, however, is a connectionless protocol; being connectionless means that UDP connections work like a fire hose of data moving from one IP address (the source address) to another (the destination address). Because of the way the Internet works, though—it is a large packet-switched network—these packets don't always arrive in order. For something like loading a web page, this would be a huge problem. For other uses, however, it makes perfect sense to have data arrive in whatever order it received.

Voice over IP (VoIP) calls, for example, usually use the UDP protocol. It's more important for the data to get to its source, even if...