Financial Daily from THE HINDU group of publications
Wednesday, Jan 02, 2002

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A firewall system is designed to prevent unauthorised access to or from a private network. Firewalls can be implemented in both hardware and software, or a combination of both. Firewalls are frequently used to prevent unauthorised Internet users from accessing private networks connected to the Internet, especially intranets. All messages entering or leaving the intranet pass through the firewall, which examines each message and blocks those that do not meet the specified security criteria.

Digital signature

A digital code that can be attached to an electronically transmitted message that uniquely identifies the sender. Like a written signature, the purpose of a digital signature is to guarantee that the individual sending the message really is who he or she claims to be. Digital signatures are especially important for electronic commerce and are a key component of most authentication schemes. To be effective, digital signatures must be unforgeable. There are a number of different encryption techniques to guarantee this level of security.


A metaphor for describing the non-physical terrain created by computer systems. Online systems, for example, create a cyberspace within which people can communicate with one another (via e-mail), do research, or simply window shop. Like physical space, cyberspace contains objects (files, mail messages, graphics, etc.) and different modes of transportation and delivery. Unlike real space, though, exploring cyberspace does not require any physical movement other than pressing keys on a keyboard or moving a mouse.

Virtual memory

What do you do when you run out of real random access memory (RAM)? Easy. Pass it off to virtual memory. To do this you need a virtual memory manager (usually a function of the operating system) that maps chunks of data and code to storage areas that aren't RAM. Virtual memory is really a part of your hard disk called a swap file, dedicated as a storage area for bits of data in RAM that aren't being used much. By freeing up RAM, you're virtually increasing the amount of working memory available to you.


A cache (pronounced, cash) is a place to store something temporarily. The files you automatically request by looking at a Web page are stored on your hard disk in a cache subdirectory under the directory for your browser (for example, Internet Explorer). When you return to a page you've recently looked at, the browser can get it from the cache rather than the original server, saving you time and the network the burden of some additional traffic. You can usually vary the size of your cache, depending on your particular browser.

G. Rajah

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