What is a network?
When you have more than one computer or device connected together, you have a network.
A network allows devices to send each other data in the form of 0's and 1's (bits or binary digits). |
Four kinds of networks
LAN |
Local Area Network; wired with NIC & network cables; for small to medium-sized areas like a room or a building |
WLAN |
Wireless Local Area Network; wireless, uses Wi-Fi technology, connected by WNIC (wireless NIC), routers, access points; for small areas like a building |
WAN |
Wide Area Network; wired, may use submarine cables; connects many networks together over a large area (i.e. city, country, the world) |
WPAN |
Wireless Personal Area Network; wireless, uses Bluetooth technology, connected by WNIC (wireless NIC); devices connect directly to each other; for a very small area (a room) |
Network devices
NIC |
Network interface card; a card inside a device or computer that allows it to connect to a network; usually has a port, i.e. a place to connect a network cable; a WNIC is a wireless NIC and lets you connect to Wi-Fi or Bluetooth. |
Network cable |
A long cable that carries electrical signals from the NIC of one device to the NIC of another one. |
Router |
Connects different types of networks together, i.e. a LAN to a WAN; they help to send packets of data to the correct destination, i.e. receiver. |
Hub |
Allows devices to connect to others to share data; non-intelligent (they send data everywhere and don't try to look for the correct receiver). |
Switch |
Allows devices to connect to others to share data; intelligent (they send data only to the correct receiver). |
Bridge |
Connect LANs together to make one large LAN. |
Modem |
"Modulator/Demodulator"; carry digital signals over an analogue cable (like a telephone cable); usually used to connect to an ISP (Internet Service Provider) |
The World Wide Web
The WWW or World Wide Web is one of the most popular platforms for internet services. |
A website is a set of pages built using technologies like HTML, CSS, and Javascript. Websites can be about any topic and do many different things. |
Websites are stored on web servers, which use a protocol called HTTP to display websites. |
HTTPS ("secure HTTP") is a secure version of HTTP. This means it keeps all the website's data private when you connect. |
Web browsers are software apps that help users connect to websites. They include include Chrome, Firefox, Safari, Opera, etc... |
A web browser has a large space to display websites, and other parts like navigation (back/next) buttons, a reload button, and an address bar where URLs are entered. |
Web search
Search engine |
A website, or part of a website, that allows you to search for different things, like text, pictures, music, or video. Examples of search engines include Google, Bing, Yahoo, Baidu, Yandex... |
Search keyword |
Also called search term. A word related to the kind of thing you're looking for. An example of search keywords might be "Blackpink video". |
Search results |
Things that a search engine returns after you search with certain keywords. For instance, searching with the keywords "Blackpink video" might return a list of music videos by Blackpink. |
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What is the Internet?
A worldwide network of networks |
A global, public network of computers |
The world's largest WAN |
Not the same as an intranet! |
What is the Internet used for?
Many things! Including... |
Browsing web pages using the World Wide Web (WWW) |
Sending and receiving emails |
Using search engines to do research, e.g. for school projects |
Sharing files and information |
Video conferencing (face to face discussion using webcam, e.g. MS Teams or Zoom) |
Voice calls (like Skype or Zalo) |
Streaming music and video (like YouTube or Spotify) |
Online banking |
E-commerce, i.e. online shopping |
Advertising |
Blogging (writing articles or journal entries) or vlogging (making video journals) |
Social media |
Playing multi-player online games |
Packets & Routing
To send data across the Internet, a router breaks it into small pieces called packets. These packets always carry a message or part of a message, and the IP address of the computer that sent the message (sender) and the computer that should get the message (receiver).
An IP address is like the address of a house. It tells the router where to find the receiver, so it can send the message to the right place. There are two kinds of IP addresses: IPv4 and IPv6.
Example of IPv4: 192.168.0.1
Example of IPv6: 2001:0db8:0000:0000:0000:8a2e:0370:7334
The router will look at its neighbours to find the best "road" to send the message. The "road" that the message takes is called its route. Routers look at the receiver's IP address to help them decide on the best route. This is called routing. Every packet can take a different route. If a network connection breaks down (e.g. because a cable breaks), routers can help packets find a new route. This is called re-routing. Eventually, the packet will find its way to the right place. Yay! |
URLs
A URL, or Uniform Resource Locator, shows where to find a file on the Internet. |
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"https://" is the protocol. This URL uses the HTTPS protocol, which is used to send data securely. |
"images.techadvisor.com" is the website address. It is made up of the domain host (www), the domain name (techadvisor), and the domain type (com). Sometimes, there is also a country code, like "uk" for the United Kingdom. |
"/cmsdata/slideshow/3634008/" is the path. This is like a list of folders that contain the file. |
"funny_tech_memes_2.jpg" is the file name. This one ends in ".jpg", so we know this is a JPEG image file. |
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