Quick definitions

Bandwidth Refers to the size and quantity of information 'flowing' to and from your website. Whenever you upload information to your website or whenever visitors access information from your site, the number of bytes (basic units of measurements for calculating data or file sizes) transmitted during a period increases. If your website has lots of visitors, or if people regularly access large files or web-pages on your site this would require more bandwidth than a site with, for example, fewer visitors or where information was largely text-based.
Extranet A private web based application which may be accessed only by 'invitation'. Different categories of visitors may be granted different permissions which restrict the information they have access to or what changes they are allowed to make. Extranets may be used for example to allow your suppliers or customers to capture and distribute confidential information, order status details, invoices etc. An extranet can be set up to use secure external hosting services, or to provide restricted access to web applications on your organisation's local server computers - or a combination of both.
Firewall Specialist equipment or software that prevents access to your computer, private network, server computer or website by unauthorised users. All inbound and outbound access attempts are intercepted by the firewall, which blocks any 'transmission' unless it conforms to the security rules defined for your computer or website. In effect, your systems remain safe and hidden from attack behind the firewall. Only those with the correct authorisation are allowed past (in either direction).
Intranet A private web-based application accessible only to users within an organisation who have been granted the necessary permissions. Often, an intranet will reside on the organisation's own private network(s), but could also be hosted on a secure external web-server.
Web Server - Dedicated A computer used exclusively to host your website or web-application. This option is favoured for business critical sites or applications where security, performance, up-time, bandwidth or resilience are paramount. It also avoids the possibility of another website / application running on the same computer (as with a virtual server) having an adverse impact on your application should it 'crash'. This is a bit like purchasing an ocean-going yacht - for your sole use.
Web Server - Virtual A physical computer or network of computers is 'logically partitioned' into a number of 'virtual machines', one or more of which can be allocated for your use. Following the 'shipping' metaphor, this is similar to renting a cabin and services on a cruise-liner, where each occupant has their own private space but can share certain facilities. For the most part, everything runs smoothly. However, on the rare occasions when a majority of passengers wanted to use the restaurant or pool at the same time, or if everyone wanted to use the staircases simultaneously, there could be problems. And just as fire in one cabin could have severe consequences for other passengers, with a virtual server arrangement it is possible (although rare) that a catastrophic failure on one server could impact on one or more virtual servers sharing the same physical device.
©Ingenuus Ltd. 2004