QGIS has been designed with a plugin architecture. This allows many new features/functions to be easily added to the application. Many of the features in QGIS are actually implemented as either core or external plugins.
Managing plugins in general means loading or unloading them using the Plugin Manager. To deactivate and reactivate external plugins, the Plugin Manager is used again.
Figure Plugins 1:
The Installed menu of the Plugin Manager lists all the available plugins and their status (loaded or unloaded), including all core plugins and all external plugins that have been installed and automatically activated using the Get more menu (see Section Loading an external QGIS Plugin). Those plugins that are already loaded have a check mark to the left of their name. Figure_plugins_1 shows the Installed dialog.
To enable a particular core plugin, click on the checkbox to the left of the plugin name, and click [OK]. When you exit the application, a list of loaded plugins is retained, and the plugins are automatically loaded.
External QGIS plugins are written in Python. They are by default stored in either the ‘Official’ QGIS Repository, or in various other external repositories maintained by individual authors. You can find the external plugins in the Get more menu.
Detailed documentation about the usage, minimum QGIS version, homepage, authors, and other important information are provided for the ‘Official’ QGIS Repository at http://plugins.qgis.org/plugins/. For other external repositories, they might be available with the external plugins themselves. In general it is not included in this manual.
Currently there are over 150 external plugins available from the ‘Official’ QGIS Repository. Some of these plugins offer functionality that will be required by many users (for example: providing the user with the ability to view and edit OpenStreetMap data, or to add GoogleMap layers) while others offer very specialized functions (for example: Calculate economic pipe diameters for water supply networks).
It is, however, quite straightforward to search through all the available external plugins by providing keywords, choosing a named repository and/or filtering on the status of plugins (currently installed or uninstalled in your system). Searching and filtering is done from the QGIS Python Plugin Installer
Add more repositories
To add external author repositories, open the Plugin Installer Manage and Install Plugins, go to the menu Settings, and click [Add] (see figure_plugins_2). If you do not want one or more of the added repositories, they can be disabled via the [Edit...] button, or completely removed with the [Delete] button.
As such, we cannot take any responsibility for them. You can also manage the repository list manually, that is add, remove, and edit the entries. Temporarily disabling a particular repository is possible by clicking the [Edit ...] button.
Figure Plugins 2: