Web Crawler

Web crawler, sometimes called a spider or spiderbot and often shortened to crawler, is an Internet bot that systematically browses the World Wide Web, typically used by search engines for the purpose of Web indexing.

Web search engines and some other websites use Web crawling or spidering software to update their web content or indices of other sites’ web content. Web crawlers copy pages for processing by a search engine, which indexes the downloaded pages so that users can search more efficiently.

Crawlers consume resources on visited systems and often visit sites without approval. Issues of schedule, load, and “politeness” come into play when large collections of pages are accessed. Mechanisms exist for public sites not wishing to be crawled to make this known to the crawling agent. For example, including a robots.txt file can request bots to index only parts of a website, or nothing at all.

The number of Internet pages is extremely large; even the largest crawlers fall short of making a complete index. For this reason, search engines struggled to give relevant search results in the early years of the World Wide Web, before 2000. Today, relevant results are given almost instantly.

Crawlers can validate hyperlinks and HTML code. They can also be used for web scraping.

A web browser, or simply “browser,” is an application used to access and view websites. Common web browsers include Microsoft Internet Explorer, Google Chrome, Mozilla Firefox, and Apple Safari.

The primary function of a web browser is to render HTML, the code used to design or “mark up” webpages. Each time a browser loads a web page, it processes the HTML, which may include text, links, and references to images and other items, such as cascading style sheets and JavaScript functions. The browser processes these items, then renders them in the browser window.

Early web browsers, such as Mosaic and Netscape Navigator, were simple applications that rendered HTML, processed form input, and supported bookmarks. As websites have evolved, so have web browser requirements. Today’s browsers are far more advanced, supporting multiple types of HTML (such as XHTML and HTML 5), dynamic JavaScript, and encryption used by secure websites.

The capabilities of modern web browsers allow web developers to create highly interactive websites. For example, Ajax enables a browser to dynamically update information on a webpage without the need to reload the page. Advances in CSS allow browsers to display responsive website layouts and a wide array of visual effects. Cookies allow browsers to remember your settings for specific websites.

While web browser technology has come a long way since Netscape, browser compatibility issues remain a problem. Since browsers use different rendering engines, websites may not appear the same across multiple browsers. In some cases, a website may work fine in one browser, but not function properly in another. Therefore, it is smart to install multiple browsers on your computer so you can use an alternate browser if necessary.

web browser (commonly referred to as a browser) is a software application for accessing information on 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. For a user, a search engine is just 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 smartphones. In 2020, an estimated 4.9 billion people used a browser, with more than half of them in Asia. The most used browser is Google Chrome, with a 63% global market share on all devices, followed by Safari with 19%. Other notable browsers include Firefox and Microsoft Edge.

A software application used to access information on the World Wide Web is called a Web Browser. When a user requests some information, the web browser fetches the data from a web server and then displays the webpage on the user’s screen.

History of Web Browser

Today web browsers are easily accessible and can be used on devices like computer, laptops, mobile phones, etc. but this evolution of making browsers available for easy use took many years.

Given below are some salient points which one must know with regard to the history of web browsers:

  • “WorldWideWeb” was the first web browser created by Tim Berners Lee in 1990. This is completely different from the World Wide Web we use today
  • In 1993, the “Mosaic” web browser was released. It had the feature of adding images and an innovative graphical interface. It was the “the world’s first popular browser”
  • After this, in 1994, Marc Andreessen (leader of Mosaic Team) started working on a new web browser, which was released and was named “Netscape Navigator”
  • In 1995, “Internet Explorer” was launched by Microsoft. It soon overtook as the most popular web browser
  • In 2002, “Mozilla Firefox” was introduced which was equally as competent as Internet Explorer
  • Apple too launched a web browser in the year 2003 and named it “Safari”. This browser is commonly used in Apple devices only and not popular with other devices
  • Finally, in the year 2008, Google released “Chrome” and within a time span of 3 years it took over all the other existing browsers and is one of the most commonly used web browsers across the world

Functions of Web Browser

Our dependency on the Internet has massively increased. Stated below are functions of web browsers and how are they useful:

  • The main function is to retrieve information from the World Wide Web and making it available for users
  • Visiting any website can be done using a web browser. When a URL is entered in a browser, the web server takes us to that website
  • To run Java applets and flash content, plugins are available on the web browser
  • It makes Internet surfing easy as once we reach a website we can easily check the hyperlinks and get more and more useful data online
  • Browsers user internal cache which gets stored and the user can open the same webpage time and again without losing extra data
  • Multiple webpages can be opened at the same time on a web browser
  • Options like back, forward, reload, stop reload, home, etc. are available on these web browsers, which make using them easy and convenient

Types of Web Browser

The functions of all web browsers are the same. Thus, more than the different types there are different web browsers which have been used over the years.

Discussed below are different web browser examples and their specific features:

1. WorldWideWeb

  • The first web browser ever
  • Launched in 1990
  • It was later named “Nexus” to avoid any confusion with the World Wide Web
  • Had the very basic features and less interactive in terms of graphical interface
  • Did not have the feature of bookmark

2. Mosaic

  • It was launched in 1993
  • The second web browser which was launched
  • Had a better graphical interface. Images, text and graphics could all be integrated
  • It was developed at the National Center for Supercomputing Applications
  • The team which was responsible for creating Mosaic was lead by Marc Andreessen
  • It was named “the world’s first popular browser”

3. Netscape Navigator

  • It was released in 1994
  • In the 1990s, it was the dominant browser in terms of usage share
  • More versions of this browser were launched by Netscape
  • It had an advanced licensing scheme and allowed free usage for non-commercial purposes

4. Internet Explorer

  • It was launched in 1995 by Microsoft
  • By 2003, it has attained almost 95% of usage share and had become the most popular browsers of all
  • Close to 10 versions of Internet Explorer were released by Microsoft and were updated gradually
  • It was included in the Microsoft Windows operating system
  • In 2015, it was replaced with “Microsoft Edge”, as it became the default browser on Windows 10

5. Firefox

  • It was introduced in 2002 and was developed by Mozilla Foundation
  • Firefox overtook the usage share from Internet Explorer and became the dominant browser during 2003-04
  • Location-aware browsing was made available with Firefox
  • This browser was also made available for mobile phones, tablets, etc.

6. Google Chrome

  • It was launched in 2008 by Google
  • It is a cross-platform web browser
  • Multiple features from old browsers were amalgamated to form better and newer features
  • To save computers from malware, Google developed the ad-blocking feature to keep the user data safe and secure
  • Incognito mode is provided where private searching is available where no cookies or history is saved
  • Till date, it has the best user interface

Apart from these, Opera Mini web browser was introduced in 2005 which was specially designed for mobile users. Before the mobile version, the computer version “Opera” was also released in 1995. It supported a decent user interface and was developed by Opera Software.