How the web works
The internet serves up content from anywhere. Users find content using a telecommunications network and a web browser.
A user connects to the
internet using a telecommunications network (dial up, cable, satellite, wireless).
The web browser
requests a web page. The browser asks for files located at a web address (called a URL
or URI)
The
request goes to a name server. The name server matches to web address to the real
location of the files for the webpage and passes on the web browser's request to a file
server at that location.
The file server
responds to the request by sending off the files for the webpage. These are routed to
the web browser in pieces (called packets).
The browser
collects the packets and makes them up into a web page. The packets contain content and
instructions for presenting it.
The browser displays the
assembled webpage for the user. Provided the instructions for presentation are
adequate, the content can be displayed in different ways (eg on a computer screen,
printed page, audio output).
Different browsers
have different strengths and weaknesses. Most people use a visual browser (like
Internet Explorer). and view webpages on the screen. Others may use a text-only browser
and braille display. Serving webpages to everyone depends on separating the content
from the instructions for presentation.
The browser may user a
helper program (called a plug in) to render the pages, or do something specific on the
webpage (like play a piece of music). If the browser doesn't have the plug in needed to
see the content, the user will have to stop and download it (but often won't bother).
Some people
use non-standard devices to browse the web (eg people with impairments to their vision
or mobility). Serving webpages to people using assistive technology depends on
separating the content from the instructions for presentation and the instructions for
presentation being well though out.
The webpage may contain a
form. A form is a way to collect information from the user so the browser and file
server can interact (eg buy some flowers, subscribe to a newsletter).
How fast a webpage is
served up and displayed depends on several things - the amount of packets needed to
make the page, efficiency and location of the file server, speed of the user's PC,
amount of data the user's telecommunication connection can handle, volume of traffic on
the internet, how much guessing the browser has to do to make up the page (sometimes
the instructions for presenting webpages aren't good).
Usually
files are requested by the browser using a method called HTTP (hypertext transfer
protocol). Browsers can request files by other methods. A common one is FTP (file
transfer protocol) - this is used for downloading and uploading files.
Selecting
and viewing a webpage is like playing a hole on a golf course. The target is clearly
identified and there is an optimum route to reach it, but there are potential obstacles
along they way that could make the journey difficult.
Users are interested in the content, not how it's served.