Sandboxie is a proprietary sandbox-based isolation program developed by Ronen Tzur, for 32-bit Windows NT-based operating systems. It creates a sandbox-like isolated operating environment in which applications can be run or installed without permanently modifying the local or mapped drive. An isolated virtual environment allows controlled testing of untrusted programs and web surfing.

Sandboxie runs your programs in an isolated space which prevents them from making permanent changes to other programs and data in your computer.

When you run a program on your computer, data flows from the hard disk to the program via read operations. The data is then processed and displayed, and finally flows back from the progam to the hard disk via write operations. For example, if you run the Freecell program to play a game, it starts by reading the previously recorded statistics, displaying and altering them as you play the game, and finally writing them back to disk for future reference. Sandboxie changes the rules such that write operations do not make it back to your hard disk.

Protecting your Freecell statistics using Sandboxie may be a good idea when a less qualified player comes along, but you will probably want to play most of your games outside the sandbox. On the other hand, you may want to run your Web browser inside the sandbox most of the time. This way any incoming, unsolicited software (spyware, malware and the like) that you download, is trapped in the sandbox. Changes made to your list of Favorites or Bookmarks, hijacking of your preferred start page, new and unwanted icons on your desktop - all these, and more, are trapped in and bound to the sandbox.