6.1. Netscape Navigator 4.x

• Very old.
• Relatively Unmaintained.
• Buggy and Incomplete CSS support.
• Incomplete or completely lacking support for newer standards.
• As a result, it tends to break under many pages.
• Very small (and descreasing) use percentage, but can still be found in god-forsaken (mainly old) installations.
• My advice: ignore completely. Supporting it is not worth the trouble. Your kilometrage may vary, however. (depending on the circumstances)