The hypertext you write is stored (or, at least, sent over the Internet) in HTML language. Currently (1991-1997) some people write the HTML code themselves while others use tools, such as hypertext editors, to create the HTML documents.
What sort of HTML tags should you use? You do need to be concerned with the sort of HTML you or your software produces.
The first reason is that if you are careful to use standard HTML which is understood in the same way by software across the world, this is part of making your document "device independent" as just discussed.
The second reason is you may want the data you are creating to be still accessible in the future: you want it to be independent of future evolutions in software. The likely life of your document is worth some thought. Even if it will become obsolete, what would the damage be if it ceased to be readable by typical users in 5, 10 or 20 years time? This also applies if you are writing "virtual hypertext" -- in other words you are writing a program which generates hypertext automatically on the fly. Such programs can become part of the way your company lives and breaths, and if they work, they could still be around for a long time.
It may be tempting to use particular features of some "extended" "HTML" , which are proprietary and effectively require that software used to browse, generate or handle the data comes from a particular company. In some cases this may be appropriate. However, some people may still remember the great costs companies went through to move from proprietary networks to the Internet, and from one proprietary operating system to another. Company fortunes and products change dramatically over time, so think of the possible cost you may be letting your heirs in for.
HTML standards are developed by the World Wide Web Consortium, and copies of the documents are available from the Technical Notes list. For a detailed look at the current state of developments in this area, check out the W3C HTML activity.
There are a number of tools which are available for testing whether your document in fact conforms to a given standard. It might be wise to use them: regularly if you write your own HTML, or occasionally if you use editing software. (See also: testing your document .)
Clearly, you need for the same reason to be careful which formats you use for images, applets, animations, sounds and videos and whatever. For images. In 1997, GIF89a and JPEG are safe, and PNG (an improvement on GIF) is becoming acceptable. But it is far beyond the scope of this guide to make a survey of which standards are reliable. The press has an important job in assessing these things, and endorsement by bodies such as W3C, the IETF and ISO is of course very significant.