how to use URLs in laravel

URL::full();
URL::current();
URL::previous();
URL::to('foo/bar', $parameters, $secure);
URL::action('FooController@method', $parameters, $absolute);
URL::route('foo', $parameters, $absolute);
URL::secure('foo/bar', $parameters);
URL::asset('css/foo.css', $secure);
URL::secureAsset('css/foo.css');
URL::isValidUrl('http://example.com');
URL::getRequest();
URL::setRequest($request);
URL::getGenerator();
URL::setGenerator($generator);