The internet

The Internet evolved over the past thirty years from a fledging experiment with four computers into a vast information network that connects millions of microcomputers, minicomputers and mainframe computers. As of 1998, the Internet had more than 100 million users world wide, and that number is growing rapidly. The Internet is decentralised by design and, remarkably, this anarchy by design works well.

Internet: A collection of local, regional and national computer networks that are linked together to exchange data and distribute processing tasks.

There are a variety of ways to access the Internet, the most common being through an Internet Service Provider (ISP). An ISP is a company that charges an ongoing fee for providing Internet access to businesses, organisations and individuals. The ISP provides the user with the necessary communications software (such as e-mail) and user account. The user supplies a modem that connects the computer to the user’s phone line. The user’s computer dials the ISP’s computer and establishes a connection over the phone line. Once connected the ISP routes data between the user’s computer and the Internet. Most ISPs offer dial-up Internet connections and electronic mail access, along with additional services. Some ISPs offer direct access to the Internet without the use of proprietary software.

The Internet connects millions of people through a collection of computer networks.

A connection that uses a phone line to establish a temporary connection to the Internet is referred to as a dial-up connection. When the user’s computer hangs up, the connection is broken. A phone line provides a very narrow pipe for transmitting data. Its typical capacity is only 28.8 thousand bits per second (bps). Using a phone line, the time to transfer the contents of a 680 megabyte CD-ROM would be over 53 hours. More rapid digital data transmission is now available from some telecoms providers in various parts of the world.

The World Wide Web was created in 1990 as an easy-to-use source of information.

World Wide Web: A computer network system that allows users to browse through information available on computers round the world.

The World Wide Web opened the Internet to millions of people interested in finding information. There are over one million Web sites around the world and the number is growing very quickly. The World Wide Web consists of documents called Web pages that contain information on a particular topic. A Web page might also contain one or more links that point to other Web pages.

Link: A reference to another document in an environment like the World Wide Web, that users can go to directly by clicking on the on-screen reference with the computer’s mouse.

Links make it easy to follow a thread of related information, even if the pages are stored on computers located in different countries. Every Web page is stored as an HTML (HyperText Markup Language) document.

HyperText Markup Language (HTML): One of the main standards that controls how the World Wide Web works; it is an SGML document type definition that determines how Web pages are formatted and displayed and thus enables information to be exchanged on the World Wide Web.

Standardised General Mark-up Language (SGML): A metalanguage that can be applied to documents in order to maintain their structure and context.

An HTML document contains special instructions called HTML tags that tell a Web browser how to display the text, graphics, and background of a Web page.

Web browsers are used to view Web pages, transfer files between computers, access commercial information services, send e-mail, and interact with other Internet users.

Web browser: A software application that enables a user to locate and view pages on a Web site. Also known as a browser.

To request a Web page the user either types in the URL (Uniform Resource Locator) address or uses a ‘mouse’ to click on a Web page link.

Uniform Resource Locator (URL): The global address of documents and other resources on the World Wide Web. URLs can point to executable files that can be fetched using FTP (file transfer protocol, ftp://) or a Web page that can be retrieved using HTTP (hypertext transfer protocol, http://).

After the http://, the next segment of the address is the server name. The server is the computer and software that make the data available. A Web server, for instance, is a computer that uses Web server software to transmit Web pages over the Internet. Most Web servers have domain names prefixed with WWW. By entering the Web server name, one accesses the site’s home page.

Home page: The main page of a Website. Typically, the home page serves as an index or table of contents to other documents stored at the site (that is, the address).

Website: A location on the World Wide Web.

A home page is similar to the title page and table of contents in a book. It identifies the site and contains links to other pages at the site. The following is an example of a home page belonging to the ICA, viewed using a particular type of browser software called Microsoft Explorer.

The Web browser is the gateway to commercial information services as well as the free sites on the Internet. A commercial information service provides access to computer-based information for a fee. In 1997, approximately 17 million people subscribed to the top four commercial information services: America On-Line, Compuserve, Microsoft Network and Prodigy.

The server sends the data for the Web page over the Internet to the computer. The data includes two things: the information the user wants to view and a set of instructions that tells the browser how to display it. The instructions include specifications for the colour of the background, the size of the text, and the placement of the graphics. Additional instructions tell the browser what to do when the user clicks on a link. The browser’s menu and tool bars help users navigate the Web as they follow the links. The Back and Forward buttons trace and retrace the users’ path through the links being followed from one Web page to another. The browser stores and can display a list of the pages being visited during each session. The browser can also store a list of favourite sites, often called bookmarks, to permit the user to jump directly to the site they wish to see instead of having to enter its URL every time.

Users can find information on the Web by using a search engine. There are a number of Web sites that provide search facilities, and the Internet Service Provider will links to these sites.

Search engine: A program that searches documents for specified keywords and returns a list of documents where the keywords were found.

COMPUTER APPLICATIONS

Applications software includes programs that users access to carry out work. This lesson examines two applications that may be of particular use to the student: databases and electronic mail (‘e-mail’). It introduces key concepts related to how databases and e-mail work.

Please remember, this lesson is not intended to provide a comprehensive explanation of the technical details of all applications. Other applications would be word processing, spreadsheets and presentations. A brief description of these types of software can be found in Lesson 1.

DATABASES

A database is a collection of information stored on one or several computers.

Database: A structured assembly of logically related data designed to meet various applications but managed independently of them.

More specifically, a database is a self-describing collection of integrated records. A database is self-describing in that it contains, in addition to the user’s source data, a description of its own structure (such as in a data dictionary). It is the data dictionary that make data independence possible (for example, the database management system maps the data fields into records and handles other similar transformation).

A database is a collection of information stored on computers.

In the mid-1960s, large organisations began to apply the power of mainframe database technology to administrative functions. As the term ‘computer’ implies, originally most administrative uses of computers were to process figures rather than text. These were usually activities involving high volumes of numerical calculations, where the workflow was highly predictable and routine. Typical examples include payroll,

accounts administration or personnel data. These database applications were primarily organisation-wide transaction processing systems.

The limitations of file processing prevented the easy integration of data. Database technology held the promise of solving these problems so large organisations began to develop organisational databases. Companies centralised their operational data, such as purchase orders, inventory and accounting data in these databases; these database applications were primarily organisation-wide, transaction processing systems.

Originally, database processing was developed for use in the mainframe environment. However, in the late 1970s to early 1980s, database technology began to move from mainframes to PCs. As a result, database management systems gradually became more powerful and easier to use. By the mid to late-1980s, PCs were beginning to be linked together with the aid of networking, which enabled computers to send data to one another at previously unimaginable rates. In time, users wanted to share their databases as well; this led to the development of multi-user database applications on local area networks (LANs).