A digital "stamp" in a macro that confirms that the macro originates from the developer who signed it and that it has not been changed. To be able to digitally sign macro projects and to identify them as your work, you have to obtain and install a digital certificate. If you open a file or load a plug-in that contains a digitally signed macro, a digital signature is displayed on your computer as a certificate specifying the source of the macro as well as additional information concerning the identity and integrity of this source.