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How the Web Works

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The Big Picture

3:57 with Joy Kesten

Every web request starts with typing in or clicking something on the web. Often times you find what you need using a URL, but URLs can also be hidden behind hyperlinks. Included in a URL is a domain name. Domain names are really just catchy versions of IP addresses and domain name servers make the connection between domain names and IP addresses. Clients and servers are designed to talk to each other using the HTTP protocol, the common set of rules they've agreed to use.

[MUSIC] 0:00
What actually happens in between typing in teamtreehouse.com and seeing the website? 0:04
If point a is the browser on your computer, and point b is a web server 0:10
hosting teamtreehouse.com, everything in between is the cloud, right? 0:14
Well, yes and no. 0:20
In between each browser request and server response are one or 0:21
multiple pieces of software, most of them speaking to each other using 0:25
a common protocol called HTTP, or the Hypertext Transfer Protocol. 0:29
Let's start with an overview of how the Web works, and 0:35
then explore each step individually. 0:37
Every website you've browsed started with a client sending a request to a server. 0:40
A client is anything that can request a resource on the web. 0:46
A few examples are computers, laptops, phones, and tablets. 0:50
But even software programs themselves can be clients. 0:54
When a client, you and your computer, types a URL into the address bar, 0:58
you are sending a request to a server. 1:03
The internet is a net of computers all connected together by various cables. 1:07
It's made up of wires, routers, switches and 1:13
satellites, connecting the network of servers together. 1:15
These servers can perform a lot of tasks. 1:20
A few server examples are web servers that host web sites, 1:23
domain name servers that connect domain names with IP addresses, or 1:28
mail servers that send and accept email messages. 1:32
All of these things are considered part of the internet. 1:37
Housed on servers are the files, folders and media that make up webpages. 1:41
These files, folders and media are all software and 1:47
are what we're talking about when we say the web. 1:51
The web is the software that makes up websites, applications, 1:55
games, wikis and videos that you can access on a web browser. 2:00
As you know, there are a lot of different web browsers out there. 2:05
Safari, Firefox, Chrome, and Internet Explorer to name a few. 2:09
There are also many types of clients, mobile phones, apps, and games. 2:13
In order for everyone to play nicely together, they have to speak the same 2:20
language, and that language is called HTTP, or Hypertext Transfer Protocol. 2:24
Nearly all HTTP requests start with you 2:31
typing in a domain name like teamtreehouse.com. 2:34
Servers, however, use numbers to locate each other, not words. 2:39
These numbers are called IP addresses and work similarly to how phone numbers work, 2:43
with each IP address pointing to a particular server on the Web. 2:49
The service in the middle, between the domain name you type in and 2:53
the IP address used by the server, is called a Domain Name Server, or DNS. 2:58
Once the DNS finds the IP address or phone number you asked for with the domain name, 3:05
it rushes your request along to the server hosting the website. 3:11
For now, we can think of this request as a stamped, self-addressed envelope 3:16
sent to the website's IP with a return address of your computer's IP. 3:21
When the envelope is delivered to the server hosting the website, 3:27
the server sends the envelope back to you with the website you wanted. 3:31
When this happens, the HTTP trip is over and you have the thing you asked for. 3:36
Now that took a long time to explain, but usually this all happens very quickly, 3:42
like, in under a second, and it's getting faster all the time. 3:46
Now that we're familiar with the process of what happens when we surf the web, 3:50
let's break down each step in more detail. 3:54