where is web.xml role

I have read such article that include web.xml to define the taglib. As a begginer I would like to know on why we need to use web.xml to define the taglibs.

The role of web.xml is very simple .

For example
<%@ taglib uri="/WEB-INF/jsp/mytaglib.tld"
prefix="first" %>

if u dont do an enrty in web.xml u need to mention the path (uri) of the tag in every jsp.This is a bad practice as to if at any point of time u need to change the location of ur tag library u need to change the path in every jsp where it has been used.


This is the entry in web.xml

<taglib>
<taglib-uri>mytags</taglib-uri>
<taglib-location>
/WEB-INF/jsp/taglib.tld
</taglib-location>
</taglib>

after u make theentry in web.xml the above tag directive looks like this

<%@ taglib uri="mytags"
prefix="first" %>