The quantum Hall effect is a phenomenon observed in two-dimensional electron systems subjected to low temperatures and strong magnetic fields. In this state, the electrical resistance becomes quantized, meaning it takes on specific discrete values rather than a continuous range. This effect is a result of the behavior of electrons in a magnetic field, leading to the formation of edge states that conduct electricity without dissipation. This effect has significant implications in condensed matter physics and has been instrumental in defining the ohm in terms of fundamental constants. It also plays a crucial role in the study of topological phases of matter, contributing to our understanding of quantum mechanics and material properties.