AIX is one of many flavors of unix. It is generally quite stable and easier to perform day to day administration tasks since it has a menu system (smit/smitty)from which you can perform nearly all tasks from. This menu system also allows you to see the commands generated by your choices, so you're not a slave to the interface. It seems to perform memory management better than other UNIX OS'esfrom what I've seen. In AIX, commands have a stronger naming convention than in other OS'es For example: mksysb makes a system backup, mkitab makes an inittab entry, mkdir makes a directory, lsvg lists volume group info, lspv lists physical volume info, etc, etc. So AIX is a Unix operating system, as is Sun Solaris, HP/UX, and others