GNOME Shell provides core user interface functions for GNOME, like switching to windows and launching applications. User interface elements provided by GNOME Shell include the Panel at the top of the screen, the Activities Overview, and Message Tray at the bottom of the screen.
GNOME Shell extensions are small pieces of code written by third party developers that modify the way GNOME works. (If you are familiar with Chrome Extensions or Firefox Addons, GNOME Shell extensions are similar to them.) You can find and install GNOME Shell extensions using this website.
Since extensions are created outside of the normal GNOME design and development process, they are supported by their authors, rather than by the GNOME community. Some features first implemented as extensions might find their way into future versions of GNOME.
Extensions may make small changes, like moving your clock to the right-hand side of the screen, or make big changes, like arranging the windows in the Activities Overview in a different way.
The code in a GNOME Shell extension becomes part of the core operating system. For this reason, the potential exists for an extension to cause system misbehavior, crashes, or even to have malicious behavior like spying on the user or displaying unwanted advertisements. All extensions uploaded to this site are carefully reviewed for malicious behavior before they are made available for download. This process of code review is similar to the process for Firefox add-ons submitted to addons.mozilla.org.
If you encounter problems with an extension, such as a crash, make sure to report the problem using the Bug Report link on the extension's page.
The easiest way to get GNOME Shell is to install a Linux distribution that provides GNOME 3. See the Getting GNOME page on the main GNOME site to learn how to grab a Linux distribution with GNOME 3.
If you are using GNOME 3.4 or newer and installation still doesn't work,
check to make sure that the "GNOME Shell Integration" plugin is installed
and enabled in your browser preferences. Some browsers have a feature,
click-to-play, which make it so the plugin cannot start without user
intervention. Make sure that either https://extensions.gnome.org
is whitelisted for the click-to-play feature, or click-to-play is turned
off entirely. Check your browser's help for more details.
If you are behind a proxy, make sure you have configured your proxy in both your browser's configuration dialog as well as GNOME's Network panel under System Settings. GNOME Shell Extensions needs both settings panels configured for the one-click installation to work.
Some distributions don't quite package GNOME correctly. Make sure that you
have the unzip package installed.
If you have checked all of these solutions and are still having trouble
installing extensions, please file a bug report using the link in the footer
of the page, giving your GNOME version, distribution and version, what
solutions you have already tried, as well as what the Looking Glass says
in both the Extensions and Errors tabs. It's also helpful to have a copy of
the ~/.xsession-errors file from the session that you installed
extensions from.
To update your extension to the latest version, go to the extension's page, or the "Installed Extensions" page, and click the green update arrow. If there is no arrow, your extensions should be fully up to date.
System extension is installed to system-wide location (usually «/usr/share/gnome-shell/extensions»). Such extension may be used by any PC user, however it can be uninstalled only by system administrator (root). To uninstall system extension use your distro's package manager or ask your system administrator.