Sandboxie enables users to install or test different programs and run applications in a sandbox - will create a separate virtual area on your hard drive and any programs installed here will not affect the rest of computer.
Is great if you are not sure if your files aren't clean and may contain viruses, just install them using it and even you get a virus, Sandboxie doesn't let it to infect system files.
Run almost any type of program (browser, email service, software etc.) through Sandboxie and test them to see if they have malware, before installing them out of sandbox mode.
Application that are running in protected mode will be highlighted with a colored border.