JSP pageencoding and charset

In JSP, there is such a property pageencoding
Why? We all know that JSP is first translated into Servlet classes such as index_jsp.java during execution.
Pageencoding is used in this translation. The Web container does not know the JSP file encoding during translation.

JavaCode

1. <% @ Page Language ="Java" Import="Java. util .*"Pageencoding =UTF-8"%>

Note: The actual encoding of your JSP file must be consistent with that specified by pageencoding. Otherwise, the Web Container cannot read your JSP file.

There is also a contenttype = "text/html; charset = UTF-8" Here charset encoding is what?
It is used to encode response output data. If charset = 'gbk' is written here, many foreign users may display garbled characters because their machines may not support GBK encoding.