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
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.)