Web Browser:
A web browser (commonly
referred to as a browser) is application software for
accessing the World Wide Web. When a user requests a web
page from a particular website, the web browser retrieves the
necessary content from a web server and then displays the page on the
user's device.
A web browser is not the same
thing as a search engine, though the two are often confused. A search
engine is a website that provides links to other websites. However,
to connect to a website's server and display its web pages, a user must have a
web browser installed.
Web browsers are used on a range
of devices, including desktops, laptops, tablets, and smart
phones. The first web browser, called World Wide Web, was created in 1990
by Sir Tim Berners-Lee. He then recruited Nicola Pellow to
write the Line Mode Browser, which displayed web pages on dumb
terminals; it was released in 1991.
1993
was a landmark year with the release of Mosaic, credited as "the
world's first popular browser". Its innovative graphical interface made
the World Wide Web system easy to use and thus more accessible to the average
person. Marc Andreessen, the leader of the Mosaic team, soon started his
own company, Netscape, which released the Mosaic-influenced Netscape
Navigator in 1994. Navigator quickly became the most popular browser.
Microsoft debuted Internet
Explorer in 1995, leading to a browser war with Netscape. In 1998, Netscape launched what would become
the Mozilla Foundation to create a new browser using the open
source software model. This work evolved into the Firefox browser,
first released by Mozilla in 2004. Apple released its Safari browser
in 2003. It remains the dominant browser on Apple devices, though it did not
become popular elsewhere. Google debuted its Chrome browser in
2008, which steadily took market share from Internet Explorer and became the
most popular browser in 2012. Chrome has remained dominant ever
since. Microsoft released its Edge browser in 2015 as part of
the Windows 10 release. (Internet Explorer is still used on older
versions of Windows.)
In
terms of technology, browsers have greatly expanded their HTML, CSS, JavaScript,
and multimedia capabilities since the 1990s. One reason has been to
enable more sophisticated websites, such as web applications. Another
factor is the significant increase of broadband connectivity, which
enables people to access data-intensive web content, such as YouTube streaming,
that was not possible during the era of dial-up modems.
The
purpose of a web browser is to fetch content from the Web and display
it on a user's device. Once a web page has been retrieved, the
browser's rendering engine displays it on the user's device. This
includes image and video formats supported by the browser.
Web
pages usually contain hyperlinks to other pages and resources. Each
link contains a URL, and when it is clicked or tapped, the
browser navigates to the new resource. Thus the process of bringing content to
the user begins again.
Most
browsers use an internal cache of web page resources to improve
loading times for subsequent visits to the same page. The cache can store many
items, such as large images, so they do not need to be downloaded from the
server again. Cached items are usually only stored for as long as the web
server stipulates in its HTTP response messages.
Web
browsers can typically be configured with a built-in menu. Depending on
the browser, the menu may be named Settings, Options,
or Preferences. The menu has different types of settings. For
example, users can change their home page and default search
engine. They also can change default web page colors and fonts.
Various network connectivity and privacy settings are also usually
available.
Privacy:
During
the course of browsing, cookies received from various websites are
stored by the browser. Some of them contain login credentials or site
preferences. Browsers also usually provide menu items for deleting browsing
history, cache entries, and other potentially sensitive data.
An
alternative approach is the private browsing mode, in which the
aforementioned items are not stored by the browser. But this is a temporary
option, only activated when using this special mode.
Features:
The
most popular browsers have a number of features in common. They automatically
log browsing history or can be used in a non-logging private
mode. They also allow users to set bookmarks and customize the
browser with extensions. Some provide a sync service.
Most
browsers have these user interface (UI) features:
·
Allow
the user to open multiple pages at the same time, either in different
browser windows or in different tabs of the same window.
·
Back and forward buttons to go back to
the previous page visited or forward to the next one.
·
A refresh or reload and
a stop button to reload and cancel loading the current page.
(In most browsers, the stop button is merged with the reload button.)
·
A home button
to return to the user's home page.
·
An address
bar to input the URL of a page and display it.
·
A
search bar to input terms into a search engine. (In some browsers, the
search bar is merged with the address bar.)
However,
the limitations of touch screens require mobile browsers to
have a simpler UI than desktop versions. The difference is
significant for users accustomed to keyboard shortcuts.
Security:
Web
browsers are popular targets for hackers, who exploit security holes to
steal information, destroy files, and other malicious activities.
Browser vendors regularly patch these security holes, so users are strongly
encouraged to keep their browser software updated. Other protection measures
are antivirus software and avoiding known-malicious websites.
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