Quantum mechanics is a theory of how everything works.

It explains how matter is part wave and part particle.
A particle can be in same place as the same time.

It is a theory that is not like classical physics. Particles have wave like properties and it is impossible to know everything at the same time.

On a super small scall any form of measurement affects the principle.

QM is a complete theory.

Quantum mechanics deals with the micro world

Math and calculus