Arguably the most feature-rich and standards-compliant of all the browsers, Mozilla is essentially a more advanced version of Netscape. Mozilla will run on most OSes, including Windows '95 / '98, Windows NT, Windows XP, Windows 3.1, Mac OS (both classic and X), Linux, Solaris, HP-UX, IRIX, Digital UNIX, FreeBSD, NetBSD, OpenBSD, OS/2, and more.