If the applet below has been deployed in a signed jar file, then you will be prompted to trust the signer of the jar file. If you do that, the applet will be granted privileges outside of the sandbox, and will be able to read and write to your hard drive, as in the example. If you choose not to trust the signer of the jar file, the applet will be constrained by the sandbox security model. You can also opt to always trust the signer of the jar file, which means that you will not be prompted to make the choice next time you download an applet that is signed by the same person.