Regarding 'dependency', I believe this refers to a package that is required by another package. From the manual,
(emacs) Package Installation.
A package may “require” certain other packages to be installed,
because it relies on functionality provided by them. When Emacs
installs such a package, it also automatically downloads and installs
any required package that is not already installed. (If a required
package is somehow unavailable, Emacs signals an error and stops
installation.) A package’s requirements list is shown in its help
Note that you can see which packages 'require' a package by opening it's description. That is, with point/the cursor on the package in the package list, type '?':
with-editor is a dependency package.
Status: Installed in ‘with-editor-20180414.757/’ (unsigned).
Summary: Use the Emacsclient as $EDITOR
Requires: emacs-24.4, async-1.9
Required by: magit-20180515.304, git-commit-20180411.1649
It is to be expected that dependency packages are frequently targeted by autoremove. From the help for
package-autoremove (accessed via
C-h f package-autoremove):
Remove packages that are no more needed.
Packages that are no more needed by other packages in
‘package-selected-packages’ and their dependencies
will be deleted.
Meaning that once all the packages that depend on a package that was installed as a dependency are removed, you want Emacs to automatically remove that package too (or at least make it possible to do so via
package-autoremove). Indeed, packages that you deliberately install (i.e., not dependencies) will rarely, if ever, be removed by
I don't see anything in the manual about 'incompatible' packages, but by opening the description buffer for a package I have installed that is listed as 'incompatible' (show-marks in this case), I find:
show-marks is an incompatible package.
Status: Incompatible because it depends on uninstallable packages.
Perhaps there are different reasons for a package to be 'incompatible'; I would check the description for the file to be sure. And yes, it's probably best to delete 'incompatible' packages to ensure you don't run into problems with the missing dependencies. On the other hand, I have no idea how long show-marks has been incompatible, but it hasn't given me any trouble yet.
 You can find this manual page via
C-h i m emacs <RETURN> m Package Installation <RETURN>. That is, open the info system,
C-h i, select the emacs menu node,
m emacs, then select the Package Installation node,
m Package Installation.