Designing a website is not made any easier by the fact that you have no control over how it will be viewed by it's audience. Monitor settings, screen resolutions, browser type and version, operating system and many more are totally beyond your control. Too try to cater for every eventuality would be nearly impossible; you would have to produce dozens of versions of your site which would take forever!
In a bid to come to some solution on the topic I began to collect statistics on browser type and versions that people were using to view my sites, and this is what I found:
These figures are based on several websites over a six-month period. Larger studies have been carried out and have shown an even higher percentage towards Internet Explorer, which now dominates the browser market.
IE5+ and NS6+ are now much closer together than they ever were in terms of compliance to the compatibility guidelines laid down by the World Wide Web Consortium. In fact NS6 is now closer to IE5+ than it is to its previous version, NS4. Netscape has even abandoned its support for its own propriety layer system in favour of W3C supported style sheet alternatives.
You had to ask. As stated, NS6+ bares hardly any resemblance to its older cousin NS4, while IE5+ is relatively close to it's previous versions but supports the new W3C DOM. This means that to programme for legacy (older) browsers you will have to either sacrifice the more dynamic elements of your site, or produce a separate version of your site for legacy browsers with less 'fancy' bits. Far more talented designers than me would advocate designing one page to operate on all version 4, 5, and 6 browsers, but the practicalities of this would mean hours of extra work and the elongation of your site's development time.
It is a real shame to see that so few people are using Netscape 6 and I for one hope this situation improves. It is an excellent product with a super-fast engine, and if you are designing your site with IE5+ in mind, there is no reason why it should not also be compatible with Netscape 6.
Updated 2020 : note that the above post is out-of-date, given this post was originally published in 2001, but is left here for archival purposes.