Quantum physics is a theory that has been established during the first half of the 20th century. It describes nature and behavior of matter and energy at particle scales (e.g. photons). This theory had predicted phenomenon that were in contradiction with classical physics such as entanglement or quantum superposition between particles.
From the second half of the 20th century, experimental demonstrations have verified many of these predictions. While there is still ongoing research in quantum physics, quantum technology has emerged and found application in different domains such as cryptography, metrology or computing.