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### Course: Code.org>Unit 1

Lesson 2: How the Internet works

We hope you enjoyed learning about how the Internet works from our friends at Code.org and the array of inventors and engineers they invited to teach!
If you'd like to dive deeper, check out this content on Khan Academy:
• Computers and the Internet: A full course covering computer hardware, digital information storage, Internet protocols, online data security, and computing innovations.
• HTML/CSS: Learn how to make webpages with HTML tags and CSS styles in our full interactive course.
• Cryptography: Dig deep into encryption, starting with ancient ciphers and ending with the modern ciphers that power today's internet cryptography.
• Bitcoin: Learn about cryptocurrency and the math behind it.
• SOPA/PIPA: Watch this video about two U.S. bills that were proposed around cyber privacy and security.

## Want to join the conversation?

• How is binary conveyed in electric currents in copper wire?
• Typically, one uses a modem (https://en.wikipedia.org/wiki/Modem) to convert the digital signal into an analog signal (via modulation https://en.wikipedia.org/wiki/Modulation) i.e. it gets converted into an electrical wave. The more popular techniques used by the modems are amplitude, frequency and phase modulation.
• Can you recommend resources that dive deeper into cybersecurity?
• An IP address is like a mailing address, but on the Internet.

All the data going around the Internet needs to know where it's going. There's a huge network of cables and routers going all over the world to connect everything, but how do these routers know where to send the data? Every packet of data has a destination IP address marked on its front. Routers look at each packet, and decide which direction it needs to go.

Let's suppose that I, from California USA, send a packet of data to Hong Kong. (This packet might contain a request to view a website, or part of an email, or something else; it's irrelevant what the packet contains, since the IP address is stamped on the front.) The first router I hit knows to send it to San Francisco, because it knows from the IP address that the San Francisco link is the most direct path to Hong Kong. Then, it gets sent across a transpacific cable. The router at the far end of that cable sends it to the ISP of the website I'm trying to access. Finally, it gets sent to the website's server.

The IP address is a way to identify a particular computer on the Internet, so that data can be sent to it. Routers have tables that know which cable to send data along, based on the IP address.
• how did you guys learn all of this stuff and teach it?
• easy,watch the video closely. also don't enter thing that pop up randomly
• In the "HTTP and HTML" video, it is mentioned that HTML is no longer used to work with fonts and positions of words in web pages. Instead, CSS is used. Why is that so?
• Because CSS is a better, more powerful, readable and organized way to do it.
• In my reading and studying, I keep coming upon the term "port", and these ports seem to play a pivotal role in the internet. Could someone explain these to me?
• Ports are used by the computers to transmit data.

You can imagine them like a mailbox. One computer sends a packet to a receiver computer's "mailbox". Then, the receiver sends out a packet using that same "mailbox".

Different protocols and applications use different port numbers (there are thousands and thousands of port numbers).

If you want to really study the Internet (and just networking in general), I would suggest that you watch Professor Messer on youTube, specifically his Network+ playlist.
• is chrome a secure website to use
• Chrome is a web browser, not a web site.

Is it safe ?
As far as security vulnerabilities go, it is similar in safety to other major web browsers. It is used by a lot of people, so one would expect any vulnerabilities to be exposed quickly, and its maker, Google, seems to patch vulnerabilities relatively quickly.

As far as privacy goes, they do track user's activity, (some of this tracking is optional, some is not) which some may not consider to be safe.