About Browsers
We now know that the server does the servin’, but what about the other half
of the equation? The software that does the requesting is called the client.
People use desktop browsers, mobile browsers, and other assistive technologies
(such as screen readers) as clients to access documents on the Web. The
server returns the documents for the browser (also referred to as the user
agent in technical circles) to display.
The requests and responses are handled via the HTTP protocol, mentioned
earlier. Although we’ve been talking about “documents,” HTTP can be used
to transfer images, movies, audio files, data, scripts, and all the other web
resources that commonly make up web sites and applications.
It is common to think of a browser as a window on a computer monitor with
a web page displayed in it. These are known as graphical browsers or desktop
browsers and for a long time, they were the only web-viewing game in
town. The most popular desktop browsers as of this writing include Internet
Explorer for Windows, Chrome, Firefox, and Safari, with Opera bringing up
the rear. These days, however, more and more people are accessing the Web
on the go using browsing clients built into mobile phones or tablets.
It is also important to keep alternative web experiences in mind. Users with
sight disabilities may be listening to a web page read by a screen reader (or
simply make their text extremely large). Users with limited mobility may
use assistive devices to access links and to type. The sites we build must be
accessible and usable for all users, regardless of their browsing experiences.
Even on the desktop browsers that first introduced us to the wide world of
the Web, pages may look and perform differently from browser to browser.
This is due to varying support for web technologies and the users’ ability to
set their own browsing preferences.