Drupal is free,open source software that can be used by individuals or groups of users to easily create and manage many types of Web sites. Drupal is written in the php programming language. The software is ready-to-use upon download and also includes a Web-based installer and add on modules. The software supports content management, collaborative authoring, newsletters, podcasts, image galleries, peer to peer networking, file uploads/downloads and more.
Video link of designing a website using Drupal:- https://youtu.be/cRlN5oyXGqM
Opensource : Any software with its source code made available with a license in which the copyright holder provides the rights to study, change, and distribute the software to anyone and for any purpose.