Applets can't load libraries or define native methods.

An applet can't ordinarily read or write files on the host that's executing it.

An applet can't make network connections except to the host that it came from.

An applet can't start any program on the host that's executing it.

An applet can't read every system property.

Windows that an applet brings up look different than windows that an application brings up:

Figure 12.6. Applet Look

Applets can play sounds.

Applets running within a Web browser can easily cause HTML documents to be displayed.

Applets can invoke public methods of other applets on the same page.

Applets that are loaded from the local file system have none of the restrictions that applets loaded over the network do.

Although most applets stop running once you leave their page, they don't have to.