[Drupal] How to create a subtheme in Drupal

If you are a Drupal developer and not a stranger to themes and its behaviors, let us see how to create a subtheme in Drupal. A sub theme is quite similar to a theme. When we create a sub theme, it has an independent folder structure as any theme. The only difference is that it inherits everything from parent theme. There are no limits in creating subtheme for a subtheme and so on.