You can provide custom tags for JSP files using either tag handlers or JSP tag files. A tag library can contain either type of custom tag, or it can contain both types. When you bundle a tag library in a JAR file, you must include a TLD (tag library descriptor) file. A JSP container uses the TLD file to associate a URI with a tag library and its tags.
The TLD file contains:
You use the tag element to add a Java class tag handler to a TLD. You use the tag-file element to add a tag handler implemented in a tag file to the TLD.
The IDE creates a TLD file when you use the New File wizard to create a tag library. You can then use code completion in the Source Editor to edit the elements of the TLD file. For example, you will need to do this certain advanced features, including adding validators and event listeners. If you edit the TLD file directly, you can validate it as you would with a normal XML file.
For a full guide to creating and using tag library descriptors, see: