What are most important concepts in DevOps?

DevOps is an IT philosophy & it also promotes software developers and IT operations to communicate, collaborate, integrate, and automate in order to increase the pace and quality of product delivery.

DevOps is an offshoot of agile software development, created out of the necessity to keep up with the higher software velocity and throughput obtained by agile approaches.

Over the last decade, advances in agile culture and methodology have shown the need for a more comprehensive approach to the end-to-end software development lifecycle.

Agile software development refers to several iterative and incremental software development approaches.

Scrum, Kanban, Scaled Agile Framework®, lean development, and extreme programming are some of the most prominent agile techniques (XP).

Furthermore, there are six principles of DevOps Engineer.
They are as follows: Customer-Centric Action, Design with the end in mind, automate whatever you can, end-to-end accountability, cross-functional autonomous teams, and continuous improvement.