Sun Microsystems was an early pioneer in UNIX operating systems and hardware. It developed Solaris and ran it on SPARC hardware. Over time, Sun expanded into new markets like Java, Linux distributions, and x86 hardware. This allowed it to compete in both high-end 64-bit servers and commodity 32-bit servers. Key products included Solaris, Java, UltraSPARC servers, and Linux desktops and servers. Revenue came from licensing Solaris, Java, and hardware sales across different market segments.