The World Wide Web, WWW or the Web, is - in simple terms - a distributed hypermedia system. Distributed, since the information can be present anywhere. Hypermedia, because the various electronic documents are all linked together. The current state is such that these documents may be text, drawings, tables, graphics, sound, animation or video. Although all this electronic information could in principle be accessed directly via the Internet, it is the concept of the Web that has made it possible to put all these parts together into a large system. Similarly, various software tools that are available on the Internet have now been integrated into the Web, making these individual tools more transparent and easier to use by the user. In a sense, one can say that the Web is the face of the Internet network.
In order to use the WWW, you need to have access to Internet services and hence you need a connection to the Internet. Internet connections are offered by Internet providers or Online Services (America Online, Compuserve, Microsoft Network, T-Online). In most countries you can find several Internet providers or Online Services. The choice of your Internet provider or Online Service provider depends on the services and support one wants to buy. Points to keep in mind are:
As an example, EUnet is one of the major European Internet providers. The address of the international office of EUnet is: EUnet, Singel 540, NL-1017 AZ Amsterdam, The Netherlands. Tel: +31 (0)20 623 3803; Fax: +31 (0)20 622 4657; e-mail: more-info@EU.net. The WWW address (URL) is: http://www.EU.net/
You need a computer to access Internet and to use the WWW. Here are some of the requirements:
1. The choice of the PC does not really depend on which WWW browser (see software below) you are planning to use. Both Microsoft's Internet Explorer (Microsoft Windows) and Netscape's Navigator are available for IBM compatibles and Macintoshes. However, given the fact that most of the Astronomical software tools run on IBM compatibles, it is advised to use this category of PCs.
2. More memory will definitely improve performance of your PC because less swapping of applications will be needed.
3. The amount of disk space depend on the volume of data that the user(s) want(s) to retrieve from the net (data inclusive) and to store on disk.
4. Slightly more expensive modems go up to 28.800 bits/sec in compressed format, obviously improving the speed to your Internet provider and also the WWW access. Another interesting possibility is an digital ISDN connection that supports 64.000 bits/sec = 8000 byte/sec transfer rate.
Your computer must have the right software (programmes) to access the Internet and to correctly display the information obtained over the Web:
1. Choices are Window 3.1, Window 95, Mac Os, or Linux version 1.2.13. The latter OS is free of charge, come with the Xfree windowing software and supports a large number of different hardware configurations. Various astronomical processing tools have been ported to Linux. However, computer shops have only limited experience with this OS. Macintosh can also be considered, but has the disadvantage that there are less astronomical software tools available.
2. Both Microsoft's Explorer and Netscape's Navigator are available for Window 3.1, Window 95, Macs. Netscape's Navigator also supports more expensive operating systems like HP-UX, SG/IRIX, SunOs, and Sun Solaris. Although there is not much difference in term of functionality, we advice Netscape's Navigator.
3. Provided with the modem.
Authors: Rein Warmels (ESO), Michael Naumann (ESO), Anders Västerberg (EAAE)