I would like to find a free online course, not too hard. I have minors in math and physics, but have been away for awhile. Maybe something on youtube. If someone knows of a decent course that I could educate myself with I would appreciate any info on it. Thanks in advance, Malcolm. 
Quantum mechanics is a branch of physics that studies the behavior of matter and energy on a very small scale, such as atoms and subatomic particles. It describes how these particles interact and how they behave differently from classical mechanics.
Quantum mechanics is important because it helps us understand and explain many phenomena in the natural world that cannot be explained by classical mechanics. It has also led to the development of new technologies, such as quantum computing and cryptography.
Quantum mechanics differs from classical mechanics in that it considers particles to have both wave-like and particle-like properties, and it allows for uncertainty in the behavior and position of particles. It also introduces the concept of superposition, where a particle can exist in multiple states simultaneously.
Learning quantum mechanics requires a strong foundation in mathematics and physics. It is recommended to start by studying classical mechanics, electromagnetism, and linear algebra. There are also many online resources, textbooks, and courses available that can help in learning quantum mechanics.
Quantum mechanics has many practical applications in various fields, such as electronics, telecommunications, and cryptography. It is also used in medical imaging, nuclear energy, and materials science. Some examples of quantum technologies include quantum computers, quantum sensors, and quantum cryptography systems.