INTERNET AND NETWORKING TERMINOLOGY FOR BEGINNERS
As you go through these forums, you may have come across some terms that you don’t understand.This overview is designed to take some of the mystique out of these terms and explain them in a way a beginner can understand (hopefully).
Wherever possible, I’ll try and explain these terms and concepts using the analogy of the phone system. If you’re a teenager - it’s a given, but I am assuming that the rest of you know how to use a phone.
The explanations aren’t of a technical nature. They’re more designed to explain the concept, rather than the nuts and bolts. Sort of like - “Look - car go vroom!”, rather than “I think the gearing ratio is a little too high to sustain the torque through the optimum powerband of the motor.”
There’s a fair bit of reading here, but please don’t be intimidated - it’s pretty much laid out how I explained this type of stuff to my mum, and she got it, so there’s hope for every one of you. 
THE BIG STUFF
NETWORK
A network is simply a collection of devices that are connected to each other and can make themselves (and their resources) available to other devices that are connected. Printers, scanners, computers, switches, routers - individually these things are just what they are, but when they are connected correctly, they can form a network.
In a telephone sense, a phone handset is just that - great fun to press the buttons but can’t do much on it’s own. Plug it in to a phone socket and the usefulness of the phone extends way beyond just pressing buttons. In this case the phone is part of the network, the local phone exchange and the rest of the phone companies wires and stuff completes the network. And the phone on the other end of the line, of course.
LAN (Local Area Network)
A Local Area Network (LAN) is exactly what it’s name implies - a network that has strictly defined, local boundaries and the resources connected to that network can’t see beyond it’s boundaries.
In a phone sense, this would be like a set of intercoms in your house. Each intercom can connect to and talk to the other intercoms in the house, but they can’t connect to the phone system and talk to anyone outside your house.
INTERNET
Ah, the internet. How would we have wasted so many hours without it?
The internet, as a whole, is just an extremely big number of networks that have a series of connections between them and allow communications to pass from one network to the other. The term “Internet” actually means “Internetwork”.
In a phone sense, the internet is the global phone system that allows you in your home to call anyone, anywhere else in the world, providing they have a phone that can accept calls from the global phone system.
HARDWARE - THE STUFF YOU PLUG CABLES INTO
NIC (Network Interface Card)
To connect to a network, you have to have a Network Interface Card (NIC). This is either a separate card installed in your PC or integrated into the motherboard (the biggest thing with chips on it) in your PC. Each NIC contains a unique address known as the MAC address. That’s right - EVERY NIC ever made in the world has a unique address. This is one of the ways that serves to differentiate one network connected device from another network connected device. It is the critical bit that sends and receives the data across the network you are connected to. It sends music, pictures, words etc. in the form of electronic “dots and dashes” across the network.
In a phone sense, the NIC is the phone handset. It is what connects your data (your voice) to your network (your phone service). Just as your phone transmits an electronic representation of your voice across the phone service, the NIC transmits an electronic representation of your data across the network.
HUB
A hub is a small box with several computer cable connections in it. It allows several computers to be connected together. When you send data to another device through a hub, the data is sent to every device connected to the same hub and it is rejected by those devices the data isn’t intended for and accepted by the device is it intended for. How does it know who it’s intended for? We’ll get to that in a minute.
In a phone sense, a hub is like a box that allows a simultaneous broadcast to all the other intercoms at the same time. Only the intended recipient would listen to the actual message (like that’s ever going to happen - we all love gossip! LOL)
SWITCH
A switch is like a hub with brains. When each device that is connected to it is turned on, the switch makes a note of its MAC address. When it receives a chunk of data from someone on the network, it looks at the address of the intended recipient, checks its table of what device is connected to what swich connection and sends the data only to that recipient. This is where hubs and switches differ. A hub sends it to everyone but only one accepts. A switch sends it to the intended recipient only.
In a phone sense, this would be like an intercom that had buttons on it that you could press to connect to a particular intercom in your house, rather than sending a broadcast message to everyone (Oh well, there goes the gossip.)
ROUTER
Remember how we said a LAN had strictly defined boundaries that constrained the devices on your network? As always, there is an exception to this rule. A router is a device that can connect to two networks simultaneously. A common example of this is where you have a router installed at your house to enable connection to the internet. Computers on your LAN connect to the router (most routers have a built in switch) and the router connects to the internet. The router accepts data from your LAN intended for the internet, does a bit of fiddling and fudging with addresses and sends your request to the internet. When it gets a response back from the internet, it fiddles and fudges again and forwards the response back to the PC that originally requested it. Millions of times a second. Good thing we only have to use it, not understand it!
In a phone sense, a router is like a switchboard in your works office. The switch part of the router is like the switchboard connecting two internal extensions. The router part of the router is like when an internal extension dials an outside number. The switchboard receives the outgoing call, opens a connection to the outside phone system and passes the connection though.
CAT5 / CAT5e / CAT6
These are different types of computer cables. They all do the same thing - allow data to be transmitted along them. The numbers simply refer to their highest possible transmission speed.
In a phone sense, it’s a cable. What did you expect me to say?
THE NITTY GRITTY (OR PART THEREOF)
IP ADDRESS
Remember how NICs have a unique MAC address (Aren’t we getting good at acronyms? Get used to it - they just don’t stop in computer speak. LOL). This MAC address identifies the actual piece of hardware in your computer. To identify your computer in relation to the other computers on your LAN, an IP (Internetwork Protocol - we’ll get to protocols in a second) address is applied to the computer. Windows does a good job of assigning IP addresses automatically. Most of the time you won’t have to worry about the IP address of your PC. An IP address consists of four segments of numbers. You may have seen something like 192.168.1.1. This is an IP address. There are several classes of IP addresses. 192.168.1.1 is an example of a private address. This type of address is used on LANS and not on the internet. A router, sort of, has two NICs in it - one has a private address for your LAN, the other has an address assigned to it by your ISP and allows the router to connect to the internet. This is how it acts as a bridge between the two networks (your home network and the intenet).
In a phone sense, the IP address is like your internal extension number. It serves to differentiate between one extension and another.
I know that I’ve used the phone extension analogy before, but I’m running out of “phone” type ideas.
PROTOCOL
A protocol is a defined standard of data packaging and transmission for a given type of communication. Whew! In a nutshell - protocols are “dialects” for particular types of connections that determine the syntax two devices are going to use for a particular connection. IP is a protocol, ICMP, TCP and UDP are other common protocols.
PORT
The IP “stack” (as the IP connection bit is called) talks to the NIC and listens to the NIC to send and receive data, but it’s a bit cleverer than just being able to talk and listen to one conversation at a time. It can handle multiple inbound and outbound conversations at the same time, and it does this through what it calls ports. These are sort of like channels on a TV. You’ve got one TV set (I did tell you I was running short of phone analogies.), but it can receive and display multiple channels.
There are standard ports for different types of data. Web pages are sent from port 80 on the web server, FTP (File Transfer Protocol) uses port 21, sending email (called SMTP - Simple Mail Transport Protocol) uses port 25, receiving email (called POP - you may have already heard the expression POP mail account or POP3) uses port 110. There are over a thousand standard ports (1056, in fact) as well as many thousands of other ports that your PC will use to receive data. Luckily, this is transparent to your use of the PC.
I can’t imagine a witty phone analogy for this, so I won’t.
DNS
DNS stands for Domain Name Services and a DNS server resolves a domain name into an IP address. Every server on the internet has an IP address and this is the address that is used to send and receive data. “But how come we type in www.google.com, and we get google.com? How come we don’t have to know the IP address of the google server?”
When you request www.google.com in your browser, the request for google’s home page is sent initially to your ISP’s DNS server. The server receives your request for google.com and looks it up in its list. If it has the IP address for google.com, it inserts the IP address into your data request and forwards it to the internet. This is how the words you type get converted into the IP address of what you are looking for.
In a phone sense, this would be like you ringing your switchboard at work and asking them to put you through to XYZ Company, as you don’t know their phone number. The switchboard operator would then look up XYZ’s phone number and connect you. DNS servers don’t care how many times you ask to be connected to someone, rather than typing an IP address yourself. Switchboard operators are another matter.
FIREWALL
A firewall is a piece of software or hardware that sits in between you and the internet/LAN and controls the flow of data to and from your PC based upon a defined set of rules. These rules are designed to allow legitimate communications but to block bad communications getting into and leaving your PC.
Comodo Personal Firewall is an example, par excellence, of what is called a personal firewall. It is called a personal firewall because it is a software firewall loaded on a single PC (which may or may not be on a network) and is designed to monitor and control the flow of data in and out of that one PC. A hardware firewall would typically be in between an entire network and an intenet connected router and is designed to monitor and control the data going to or from all of the PCs on the network.
In a phone sense, a personal firewall is sort of like call screening, but automatically disconnecting the people you’ve already told the phone you don’t want to talk to. A hardware firewall is like the switchboard operator.
I hope this information is clear enough, without getting too bogged down with detail.
If there are any other PC, internet or computer technology terms you would like explained, please send me an IM on this forum, and I’ll add it to this listing.
Hope all this helps,
Ewen 
