The Copenhagen interpretation is a fundamental concept in quantum mechanics that explains how we understand the behavior of particles at the quantum level. Proposed by physicists like Niels Bohr and Werner Heisenberg in the early 20th century, it suggests that particles exist in a state of probability until they are observed or measured. This means that the act of measurement causes a particle to 'collapse' into a definite state. This interpretation emphasizes the role of the observer in determining the properties of quantum systems. It challenges classical notions of reality, suggesting that particles do not have definite attributes until they are observed. The Copenhagen interpretation remains one of the most widely taught and discussed interpretations of quantum mechanics.