[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