If a browser loads a document containing an applet and discovers that it is unable to load the applet, this text value of this property will be displayed in the space where the applet was supposed to have been loaded.

The use of this property is somewhat problematical in some browsers and completely unsupported in others.

Setting this property from a script is unlikely to be very useful, as the script is probably going to be called after the applet has failed to load.