The Servlet Mappings section lists definitions of mappings between servlet names and URLs, specifying the servlet name and URL pattern for each mapping. (None are listed here.)
The MIME Mappings section lists definitions of mappings between MIME types and file name extensions, specifying the MIME type and extension for each mapping. In this case, "text/html" is mapped to the file name extension "html", and "text/plain" is mapped to the extension "txt".