1. https://www.khanacademy.org/computing/computer- science/internet-intro
How the Internet Works
science/internet-intro

2. Wires, Cables, & wifi

3. The Internet: a physical system made to move information
Wires, Cables, & wifi
The Internet: a physical system made to move information

4. The information is made of bits
Bit=any pair of opposites (0n/off)
On=1
Off=0
8 bits=1byte
Binary

5. Internet Speed Bandwidth: Transmission capacity
Bitrate : the number of bits per second a system can transmit
Latency : time it takes for a bit to travel from the sender to the receiver

6. Cables Ethernet wire-sends information using electricity
Loses signal over long distances
Fiber optic-Sends information as light
No signal loss over distances

7. Wifi Wireless-uses radio signals to transmit information
Router receives information and then translates that information from binary into radio waves that are broadcast and your computer or smartphone can pick up
Signal loss over long distances.

8. IP Addresses and DNS

9. The internet is a network of networks
Links billions of devices together around the globe
ISP : Internet Service Provider
Protocol : a set of rules and standards used to communicate between machines

10. All devices on the internet have an unique address
IP (Internet Protocol) address : the computer sends a message to another computer with its address (a specific number that indicates its location)
DNS (Domain Name system) : associates names with the corresponding address. The Computer uses the DNS to find the IP address

11. Packets, routing, and reliability

12. Data travels on the internet indirectly-there is not a fixed path from one computer to another

13. Information travels on the Internet in a Packet

14. A packet travels one place to another on the internet a lot like how you might get from one place to another in a car, depending on traffic or road conditions.

15. Packets can be divided into smaller packets if the information to be sent is too big. Each smaller packet contains the destination address to it gets to the right place

16. Router- acts as a traffic manager to keep the packets moving smoothly

17. Each router keeps track of the different routes for sending packets and chooses the cheapest available path for each piece of data based on destination IP address. Having options for paths makes the network fault tolerant-which means the network can keep sending packets even if something goes horribly wrong. This helps make the internet reliable

18. TCP (Transmission Control Protocol) : manages the sending and receiving of all your data packets

19. HTTP and HTML

20. URL (Uniform Resource Locator) : A websites address

21. HTTP (Hyper Text Transfer Protocol) : the language used to communicate between web browsers and servers
Manage the sending and receiving of web files

22. HTML (Hyper Text Markup Language) : the language that tells the web browser how the page should look

23. Cookies: an ID number a website uses to remember who you are

24. Encryption & Public Keys

25. The internet is an open and public system which makes it vulnerable to hacking
Encryption: scrambling or changing a message to hide it.
Decryption: unscrambling the message to make it readable
Key: a secret password for unlocking a message

26. Public key-shared with everybody so anybody can encrypt a message
Asymmetric encryption: different keys for encrypting and decrypting data
Public key-shared with everybody so anybody can encrypt a message
Private key-can only be decrypted by a computer with access-only you can decrypt the message

27. HTTPs : secured

28. Cybersecurity and Crime

29. Virus is a program that gets installed (usually unintentionally) and harms the user and computer. Can spread to other computers.

30. How does a virus infect?
Trick the user to install a program that contains the virus.
Software has a vulnerability-get in a back door.
Once in, it can steal or delete files, control programs, or allow remote operation.

31. SPAm/phishing : email trick to get people to share sensitive personal information

32. Avoid getting hacked Use strong passwords
Check for authentic web addresses
Install system security updates often
Don’t install software you don’t trust.