Today, more than 20 years after the discovery of the quantum Hall effect, the number of publications in this field, at more than one paper per day, is still increasing. This remarkable fact requires some explanation. It also poses, but perhaps also answers, the question of why a new monograph entitled 'The Quantum Hall Effect' is a highly desirable addition to the literature. Originally the quantum Hall effect (QHE) was a term coined to describe the unexpected observation of a fundamental electrical resistance, with a value independent of the microscopic details of the semiconductor device. The simplest explanation of this phenomenon was based on an independent electron picture. The subsequent discovery of the fractional quantum Hall ef­ fect demonstrated that a many-body wave function and a more global view of the system is necessary to incorporate and explain interesting new aspects. Today, the quantum Hall effect has become a pseudonym for many different phenomena observed in high magnetic fields, with connections not only to solid state physics but also to theoretical descriptions in plasma physics, astrophysics, atomic physics, and high energy physics. There are even spec­ ulations that a higher-dimensional generalization of the QHE may be useful for discussing questions related to the basic properties of space.