An NBM file is a NetBeans module packaged for delivery via the web. The principal differences between it and a module jar are:

NBM files are just zip files with a special extension, which use the JDK's mechanism for signing jars. Unless you're doing something unusual, you will not need to worry about the contents of NBMs - just let the standard Ant task for NBM creation take care of it for you.

Source: NetBeans FAQ

Parent Category: Other API Tips