Ediff works with remote, compressed, and encrypted files. Ediff supports ange-ftp.el, jka-compr.el, uncompress.el and crypt++.el, but it may work with other similar packages as well. This means that you can compare files residing on another machine, or you can apply a patch to a file on another machine. Even the patch itself can be a remote file!
When patching compressed or remote files, Ediff does not rename the source
file (unlike what the patch utility would usually do). Instead, the
source file retains its name and the result of applying the patch is placed
in a temporary file that has the suffix _patched attached.
Generally, this applies to files that are handled using black magic, such
as special file name handlers (ange-ftp and some compression and encryption
packages also use this method).
Regular files are treated by the patch utility in the usual manner,
i.e., the original is renamed into source-name.orig and the result
of the patch is placed into the file source-name (_orig is used
on systems like DOS, etc.).