Accessing the global site configuration:

$jconfig = JFactory::getConfig();

Retrieving a value from the configuration:

echo $config->getValue('config.sitename');

Although rarer than accessing the global site configuration, sometimes it is necessary to access component-specific configurations. This can be done as follows:

$config = JComponentHelper::getParams('com_mycomponent');

Retrieving a value from the configuration:

echo $config->get('paramName');