The .tld files are the XML document that contains information about the whole library and about each tag contained in the library. These files are used by a web container to validate the tags and by JSP page development tools.In order to redistribute the tag files or to implement thecustom tags with tag handlers in Java, the tags in a tag library descriptor (TLD).
For more information,visit the following link:http://www.roseindia.net/jsp/Tag_Library.shtmlhttp://www.roseindia.net/jsf/netbeans/librarydescripter.shtmlhttp://www.roseindia.net/jsp/Declare_Tag_Library.shtml
Difference between tags of .tld files and java beans:
1)Tags can manipulate JSP content while beans cannot.
2)Tags usually define relatively self-contained behavior, while beans are often defined in one servlet and used in a different servlet or JSP page.
3)Tags are available only in JSP 1.1 and later, while beans can be used in all JSP 1.x versions.