2.3.3 Web browsers
Web browsers, such as Microsoft’s Internet Explorer and Netscape’s Communicator, enable people to view and navigate “web pages” over the Internet. Web pages are similar to the pages of a magazine in that they consist primarily of text and color graphics. But unlike magazine pages, web pages can contain other types of content, such as sound, animations, and video. Another difference is that individual web pages may be linked to other web pages forming a vast network, or “web”, of such pages. End users move from one web page to another by clicking the mouse on an appropriate word, phrase, or image that is linked to the target page.
More precisely, a web browser is a computer program that interprets and displays documents written in the HyperText Markup Language, or HTML. The web, or World Wide Web, is the vast collection of interconnected HTML documents, or web pages, that are delivered via the computers and networks of the Internet.
Web pages are HTML documents that generally combine three technologies: multimedia, hypertext, and programming logic in the form of JavaScript. Multimedia refers to the ability to include multiple kinds of media, such as text, graphics, photos, and audio, in a single document. Hypertext is the ability to jump from document to document by clicking on highlighted objects – such as words or pictures – that appear within the page. JavaScript is a programming language that is understood by most web browsers.
Figure 2.1: A web document as it appears using Netscape’s Communicator browser
JavaScript code can be embedded directly into web pages giving them limited program-based functionality. JavaScript tends to be used to do simple things, such as presenting an input form to a user and then checking data as it is entered by the user to ensure that it is of the appropriate type and within expected ranges.
Beyond these basic technologies, web browsers can be upgraded via plug-ins. A plug-in is a computer program that extends the capabilities of a web browser beyond its original abilities. Plug-ins enable web browsers to recognize additional types of media such as video or Flash animations. Plug-ins can also extend web browsers in other ways, such as enabling them to interpret Java Applets.
Figure 2.1 shows what Louisiana Tech University’s main web page looks like when viewed with Netscape Communicator on a Windows PC. Notice that in addition to text, this page contains graphics, such as the Tech logo, and photographs. On the left of the page is a list of topics. In order to find out more information about some aspect of the school, such as the Lady Techsters basketball team, simply click on the appropriate item, (e.g., “athletics”) and follow the appropriate links (e.g., women’s basketball).
In addition to being used for recreational and general informational purposes, web browsers have become important productivity tools in the workplace. One reason for this is that the underlying document formatting language used by the web, HTML, is a “platform neutral” way of representing information. “Platform neutral” means that an HTML document will look pretty much the same regardless of whether it is viewed using Netscape’s Communicator or Microsoft’s Internet Explorer, and regardless of whether the browser is run on a Mac, a PC, or a Unix workstation. HTML is important because it allows companies to create documents once and be assured that they can be viewed by employees regardless of the type of computer they have on their desk or which browser they happen to be using.
More and more companies are constructing internal webs. These webs contain the documents, such as manuals, procedures, training materials, and newsletters; that are essential for a company to function. Internal webs often exist on intranets, which are private networks used to connect together the computers and sub-networks of a company or organization. Intranets are distinct from the Internet, which is a publicly accessible worldwide network of networks. In addition to being private, intranets may also support much higher bandwidths, making the delivery of streaming video for employee training practical and applications such as video conferencing possible.