1. Simple Path:

In simple path we just pass the path in the url function.

Ex: $simple_path = url('admin/modules');
Output: /admin/modules

Here we just pass the relative path. and we get the relative path in simple_path variable

2. External Path:

In external path we pass the external path in the url function.

Ex: $external_path = url('http://demo.smartnetzone.com');
Output: http://demo.smartnetzone.com

Here we pass external path and get the external path in external_path variable

3. Absolute Path:

we can also get the absolute path using url function

Ex: $absolute_path = url('admin/modules', array('absolute' => TRUE));
Output: http://localhost/drupal_learning/admin/modules

Here “http://localhost/drupal_learning” is the path where the drupal is installed and including that it adds the path we pass via url function. and finally we get the absolute path as the output.

4. Fragment:

Its very useful for one page website. lets say for example, if we want to see the footer of the page, we have to scroll down to footer area. instead of that we call the footer id using fragment method.

Ex: $fragment = url('aboutus', array('fragment' => 'footer'));
Output: /aboutus#footer

Here with the path we pass an array in url function which has footer as the fragment. and when we go to the output link it will go to the footer area of aboutus page.