Microsoft* Word and Internet Explorer as well as Opera allow to save a
Web page as a single MHTML file, called Web archive. Such an archive
encapsulates all the resources necessary to display a Web page into a
single archive file that can be viewed offline. By default MHTML archives
are not supported by Firefox. The package
mhtml-firefox installs the Firefox extension
MHTML Archive Reader for all users and also binds
MHTML archives (ending in either .mht or
.mhtml) to Firefox in the desktop shell.