The goal of this document is to (hopefully) give you a clearer understanding of how computers - at home, at work, and “on the internet” work so that you'll feel more comfortable working with them.
The definition of a network is two or more computers connected together. Computers, in this context, is a very broad term. Whether at home or at work, you deal with many computers every day. At home you probably have at least a few of the following:
All of the above are bona fide computers that have a CPU, RAM, some form of data storage, and a Network Interface (hardware for connecting to a network and communicating with other devices on that network). Other devices in your house that either are computers or have computers built in include:
In short, if it can connect to your WiFi (whether you have it connected or not), it has a computer built in.
Collectively, all the computers in your house or place of business form a Local Area Network (or LAN) and they all communicate with each other via what's commonly (but not accurately) known as a “router”. (The average home “router” is actually four devices in one - a router, a firewall, an ethernet switch, and a wireless access point.)
Think of your local network like an apartment building (a fancy one with a concierge) where each apartment is one of the computer devices in your home.
Say the person in 3B wants to write a letter to the person in 12C. No reason to mail it, she writes “12C” on the envelope and hands it to the concierge, who takes it to apartment 12C and sticks it in the mail slot. This is exactly what an “ethernet switch” does.
Now let's say that, rather than writing a letter, the person in 3B uses the building's fancy intercom system to buzz the concierge and say “Please tell Janet in 12C that I'll be 15 minutes late for lunch.” This basically equates to the functionality of a wireless access point. No need to walk down the hallway and take the elevator to the first floor (analogous to network cables) to hand deliver a note to the concierge (ethernet switch) - she can do it wirelessly. Once she's given that wireless message to the concierge, he's still going to do what an ethernet switch does - deliver it to someone else in the building (on your local network). He might do that using the intercom system (wirelessly) or he might do it by writing the message on a piece of paper, taking the elevator up to 12, walking down the hall to 12C, and slide it in the mail slot of 12C's door.
Now, imagine that Jerry in 6E wants to send a package to his brother in Philadelphia. Jerry takes that package to the concierge (ethernet switch), who then walks it down the hall to the mailroom. The mailroom is analogous to the (actual) router (one of the four devices built into what you call your “router”). The basic function of a router is to allow one network to communicate with another. It does this using a “modem”. Your modem is analogous to a postal worker. His job is to take the package from your apartment building to the nearest post office (which is analogous to your Internet Service Provider or ISP).
In most cases, the connection from your modem to the modem at your ISP is physical - a cable (like the one you have if you have cable TV), a phone line (if you have “DSL” internet), or a fiber optic cable if you're fortunate to have the very best. The ISP for the winery is Valley Electric and our connection to them is wireless rather than a physical cable. An antenna on the building, here, points to an antenna on a tower some ways away. From there, cabling carries the signal to Valley Electric's headquarters. This is called terrestrial point-to-point wireless and it's not a bad system as long as the ISP doesn't assign too many subscribers to any one tower.
Devices, on your local network and on the internet use a network protocol called “TCP/IP”. You can think of this as a language - just like French, Spanish, English, Italian, or Chinese - but with a very limited and specific vocabulary.
Every device on your local network has a unique “IP Address”. It will look something like “192.168.11.209” or “10.10.17.224”. Computers on the internet all have unique IP addresses, too. For example, the IP address for Google.com is “142.250.72.142”. You could type “142.250.72.142” into the address of your web browser's address bar to get to google.com but you wouldn't want to. Just as “3780 E Kellogg Rd, Pahrump, NV, USA” is a whole lot easier to remember than latitiude/longitude coordinates like “36° 7' 5.34" N, 115° 56' 38.184" W”, “google.com” is a lot easier to remember than “142.250.72.142”.
That's what DNS does and you can think of it like the GPS of the internet. DNS is pretty involved/complicated; just remember that it takes the easy-to-remember website name and “translates” it into the numerical address that computers use to locate and connect to the right server. Without it, we'd have to remember long strings of numbers for every website.