Can anybody know about Drupal?

Yes, it's open source system, you can bulid your site with it.

Drupal is a open-source tool from which we can use their framework for our website.

Drupal is a free and open-source content management framework written in PHP and distributed under the GNU General Public License. Drupal provides a back-end framework for at least 2.3% of all websites worldwide – ranging from personal blogs to corporate, political, and government sites.

Major Search Engine "Google" is a place where you search every relevant query. It is easy to search and know all about drupal.

You can ask Mr. Google