Plugins
One of Symfony's bestselling points is its plugin architecture, not to mention the amount of plugins that are available from the community. There are two types of plugins. One is derived from a module or application, and then packaged up as a fully functional entity. The other type of plugin can be a useful tool to aid in development. Using a plugin could not be simpler. You can either install it via the CLI or download and copy it to the plugins/ folder, and then enable the plugin in the settings.yml file. Rebuild your models and clear the cache, and you're done.
To demonstrate installing and using a plugin, we are going to install DbFinderPlugin. DbFinderPlugin will be very useful to developers new to Symfony. As mentioned already, there are two ORMs with Doctrine installed by default. By using DbFinderPlugin, it will not matter which ORM you choose to start your project in, as the plugin allows you to change it. It also uses a jQuery style syntax and makes caching really easy...