Dear "How are you",
It is important not to assume that your talking partners can understand you easily.
I guess you are talking about doStartTag() method of the "tag handler".
It is from javax.servlet.jsp.tagext package.
This method performs the action associated with its custom tag. It returns one of two integer values in indicating how processing is to proceed. These two integers are final constants
javax.servlet.jsp.tagext.Tag.SKIP_BODY and javax.servlet.jsp.tagext.Tag.EVAL_BODY_INCLUDE.
Just a note in passing: Note in all the projects people use custom tags, because they are not easy to handle. But it is a good idea for you to do a few small exercises.