Torrent and peer2peer applications are strongly advised against. If you need older applications, you should be looking at places such as http://www.lowendmac.com/ or http://www.macupdate.com/ or http://www.oldmacapps.com/ or http://download.cnet.com/mac/?tag=vtredir
Do not download MacKeeper, or other system utilities. FTP download software such as RBrowser, Fetch, or Cyberduck may be needed to download from some old links. Anybody who offers a torrent may only have the beta, spyware, or a buggy release version of the said software.
Classic offers Mac OS 9 compatibility with with driverless Mac OS 9 applications. Games that required a specific GPU will not function well under Classic if at all, and require booting into Mac OS 9. Except for the Firewire 800 lacking PowerMac G4 models, DVD drive less eMacs early in 2003, DVD burner iMac 800 Mhz, and iBook G3s, booting into Mac OS 9 is not possible for newer Mac models, and only Classic was supported. July 2002 and newer Macs required system specific restore discs to install Mac OS 9. Powerbook G4s with side USB ports could not boot into Mac OS 9, but rear USB ports could. Earlier Macs that shipped with 9.2.1 or later, could only use their system specific Mac OS 9 disc to install Mac OS 9 for Classic or booting. Before then at least the 9.2.1 retail installer worked.
Classic is not available in Mac OS X 10.5 and higher or Intel Macs.
Rosetta allows PowerPC Mac OS X applications to run on Intel Macs in 10.4.4 to 10.6.8 natively that didn't require specific drivers to PowerPC, and with virtualization of 10.6 Server on Mac OS X 10.7 and later.
