Abandonware is commercial software that is no longer sold, generally for obsolete platforms. Many of us have fond memories of hours whiled away years ago on classic (pre OS X) Macs playing games like Sim City 2000 or Indiana Jones that have since become abandonware. It's now possible get ahold of many of those old games thanks to Macintosh Garden. I suspect sites like this are of somewhat dubious legality, yet they're generally left alone since this software is not available for purchase. Just don't blame me for time you waste reliving your misspent youth.