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Web 101

Years ago, my dad impressed on me the idea that if I was going to drive a car, I darned well better know how it worked. That way when things went wonky (and things always go wonky), I’d have some hope of surviving.

The internet is kind of the same way. We use it every day. We get our  news, entertainment, and social fix, but how the heck does all that work?

Here’s a quick (and simplified) view, one that hopefully will help demystify some of the magic.

First of all, when you talk about “the internet,” you’re not talking about some monolithic piece of hardware. In fact, it’s the opposite: tons of computers of varying make and size and technology, all communicating with each other.

Let’s use that idea to introduce a metaphor. Think of the internet as a city. When you refer to “the city,” your mind picture is probably a bunch of buildings and roads. Those are analogous to the data connections and computers of the internet. Being “online” or “on the internet” is analogous to having opened up a road to your computer. It can now communicate with the rest of the internet.

That brings us to the next metaphor: addresses. The key to the internet being able to function is that one computer can send data to another one, using nothing more than its numerical address. This address is called its IP address (which stands for internet protocol address). Many people shorten that to just IP. I’m not going to get into the technical stuff behind how IP addresses work. You’ll just have to take this on faith: on the internet, one computer can send information to another based on its IP address.

With me so far? The internet is a bunch of computers that can communicate with each other because each one is assigned a number (an IP address).

When you go to a web site, here’s what actually happens:

  1. You type in the web site name (i.e., www.pat-matthews.com).
  2. Your web browser sends a message to a special kind of server called a DNS (domain name server) that translates that web address into an IP address. That server sends the IP address back to your web browser.
  3. Now that it has the IP address, your computer sends the request (“get me a web page”) to the computer that is hosting the web site. This request includes the IP address of your computer.
  4. The computer that is hosting the web site sends the page information to your internet browser, using the IP address that was included in your message.
  5. Your web browser displays the web page

The information that is sent to your web browser looks nothing like what you see on the screen. Instead, it is in a markup language known as HTML (Hypertext Markup Language). There’s nothing magic about HTML. Much like the markup that used to be used at newspapers, it’s just instructions to your browser as to how the page should look.

Web pages can also contain code for your browser to run, like javascript or flash. Once that code is sent, it is actually run by your computer, without any need for more communication over the internet. It’s what we techies called “client-side.”

What happens when you send an email? A very similar thing:

  1. Your email goes out to an address that is formed like this: name@server.com (or .org or whatever).
  2. That name is translated into an IP address and the email goes to the email server on that address.
  3. The email server takes the email, decides if its spam or not, and holds it.
  4. If the recipient checks email using LiveMail or Outlook or some other email software, that software downloads the email to the recipient’s computer and deletes it from the email server.

Everything making sense so far? Okay, let’s dip our toes into the darker waters of the internet.

  • Spam: It is possible to send emails and “spoof” the sender address. This would be like me sending you a letter, but changing the return address on the envelope to someone else. That’s how a lot of spam works. Email servers can be configured (as mine is) to double-check the return address, but a lot aren’t. The reason spam exists is because the cost of sending emails is minimal. Once you have the hardware, you can send millions of emails for virtually nothing. If one of those emails convinces someone to give you money, you come out ahead.
  • Viruses & Malware: Emails can contain attachments (files that you can execute on your machine). This is where viruses come in. Whenever you run a piece of software on your computer, it has the capacity to do something bad. So the rule is simple: don’t load software that someone emails you. Even if you know the person, take a second to reassure yourself that you think that person actually sent that email. Remember: from addresses can be spoofed.
  • Privacy: If you look at step 3 above in how web pages work, you’ll notice that in order for you to view a web page, the computer that has that web page has to know your IP address. Most servers record these IP addresses. Same thing for searches. Your IP address is connected to the searches you do.
  • Tracking: I didn’t mention cookies yet. Cookies are little files stored on your computer to make browsing the web easier. When you log into a web site (like Facebook), a cookie is stored on your computer that says who you are. That way, you don’t have to keep logging in every time you change a page. The problem with cookies is that they can store other information as well. In fact, some ad companies use them to track where you’ve been.

Okay… I think that’s enough for one post. I hope it’s been helpful for you. I don’t think there’s any need for you (or anyone) to memorize all this stuff, but it’s good to have a basic understanding of what’s going on. That way, the next time something goes wonky (and it will), you have some background knowledge you can use to steer yourself out of trouble.

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Posted August 21, 2012 in Techie