Mavericks (OS X 10.9) doesn’t ship on a disc. Instead, it’s available only as an installer app downloadable from the Mac App Store, and that installer doesn’t ...

Like Lion (OS X 10.7) before it, Mountain Lion (OS X 10.8) doesn’t ship on a disc—it’s available only as an installer app downloadable from the Mac App Store ...

Formatting a hard drive along with the install of a new OS is the best option. The vast majority of operating system installations provide a "format" option as part of the installation process.