How
the Web Works:
HTML, HTTP, Servers and Browsers
SolveYourProblem.com Article Series: Web Site Design
Many people think the Internet and the web
are the same thing. In fact, the Internet is simply a global
network of computers – the web runs on top of the Internet,
and makes it useful for us. So how does the web work?
The Invention of the Web
The web was invented by a man named Tim Berners-Lee in 1989
– that's 20 years after the start of the Internet. People had
been trying to work out effective ways of sending information
around on the Internet for a while at that point (email was
invented in 1971, for example), but there hadn't been any systems
that had really harnessed the net's potential.
The
web changed everything. Berners-Lee's big idea was to
apply the idea of links to the Internet: the web would be a
mass of pages that you could move between by clicking on links.
He came up with a format for these pages (HTML), and wrote
the first web browser to view them with, as well as the first
web server for sending them to other people's web browsers.
Links
might not seem like much now, but at the time they were
revolutionary. Imagine what the web would be like if you had
to keep typing long addresses every time you wanted to move
from one page to the next, or using long numbered menu systems
that work differently from one site to the next. Without the
web, having Internet access would be pretty useless.
Servers and Browsers
Any time you use a web browser (like Internet Explorer or
Mozilla Firefox), you're using the web. How? Well, it works
like this:
1.
You open your web browser, and it goes to your home page. From there, you can click links to other websites, or to other
parts of the same website. If your home page is a search engine,
then you can type in a search and click links in the search
results. If you know the address of a site you want to go to,
you can type it in, and then click more links from there to
keep going.
2.
Each time you click a link, your browser looks at two things
about it: the name of the web server it links to, and the name
of the page it links to on that server. For example, the address
'http://www.example.com/mypage.html' tells the web browser
to get the page called mypage.html from the server at www.example.com,
using HTTP (Hypertext Transfer Protocol). This server is a
real computer, connected to the Internet, that has the page
you want to read stored on its hard disk.
3.
To find out where this server is, your web browser looks
it up using DNS (Domain Name System), which turns the text
address into a number. This IP (Internet Protocol) address
consists of four numbers between 0 and 255 – it looks like
a phone number. The Internet is set up to make it easy to find
a server anywhere in the world once you know its IP address,
and it can easily find the quickest route from your ISP (Internet
Service Provider) to the server, and establish communication.
This whole process, from DNS lookup to connection, will often
take much less than a second.
4.
Your web browser then sends an HTTP request to that web
server, and the web server responds by sending back the HTML
(Hypertext Markup Language) code for that page. Your web browser
turns this code into a page that you can view. From there,
you can click more links to start the process over again.
Of course, all this is quite simplified: modern browsers and
servers send around much more than HTML code. You can use the
web to download anything now, from pictures to programs, but
it all works in basically the same way.
If something goes wrong somewhere in this process, then you'll
get an error: 'the page cannot be displayed', for example,
usually means that the server's name was wrong, or that it
doesn't have the page you wanted. You might also see errors
saying that the server is currently too busy with other people's
requests to respond, or that the page you wanted has moved.
In each case, the best thing to do is to follow the instructions
on the error page, which usually means checking the address
and trying again.
#
# # # #
SolveYourProblem.com : 2007
> Home > Website Design Articles: Main Page
|
