Question

The World Wide Web (not to be confused with the Internet as a whole) is a set of protocols and formats that allow us to visit web pages in a browser. The “Web” part in the name refers to the fact that such pages can easily link to each other, thus connecting into a huge mesh that users can move through.

To add content to the Web, all you need to do is connect a machine to the Internet, and have it listen on port 80, using the Hypertext Transfer Protocol (HTTP). This protocol allows other computers to request documents over the network.

Each document on the Web is named by a Uniform Resource Locator (URL), which looks something like this:

  http://eloquentjavascript.net/12_browser.html
 |      |                      |               |
 protocol       server               path

The first part tells us that this URL uses the HTTP protocol (as opposed to, for example, encrypted HTTP, which would be https://). Then comes the part that identifies which server we are requesting the document from. Last is a path string that identifies the specific document (or resource) we are interested in.

Each machine connected to the Internet gets a unique IP address, which looks something like 37.187.37.82 . You can use these directly as the server part of a URL. But lists of more or less random numbers are hard to remember and awkward to type, so you can instead register a domain name to point toward a specific machine or set of machines. I registered eloquentjavascript.net to point at the IP address of a machine I control and can thus use that domain name to serve web pages.

If you type the previous URL into your browser’s address bar, it will try to retrieve and display the document at that URL. First, your browser has to find out what address eloquentjavascript.net refers to. Then, using the HTTP protocol, it makes a connection to the server at that address and asks for the resource /12_browser.html.

We will take a closer look at the HTTP protocol in Chapter 17 .

This is a book about getting computers to do what you want them to do. Computers are about as common as screwdrivers today, but they contain a lot more hidden complexity and thus are harder to operate and understand. To many, they remain alien, slightly threatening things.