• Custom JSP tag is a tag you defined. 
  • You define how a tag, its attributes and its body are interpreted, and then group your tags into collections called tag libraries that can be used in any number of JSP files. 
  • To use custom JSP tags, you need to define three separate components: 
    • the tag handler class that defines the tag's behavior ,
    • the tag library descriptor file that maps the XML element names to the tag implementations and
    • the JSP file that uses the tag library