In this chapter, we present a few selected results from a very large body of work in the general area of magnetism. X-rays can provide unique and complementary information to other techniques such as neutrons. The study of magnetism is extremely important from both a fundamental and an applied point of view. An example of its application is for computer hard drives, where a basic understanding of nano-structure magnetism is essential to the development of faster and higher-density disks. 

The study of the fluctuations of magnetic domains using coherent X-ray scattering is a new development in the study of dynamics in magnetic systems. It has allowed, probably for the first time, the observation of magnetic domain fluctuations at a first-order phase transition. This opens a new and exciting field of investigation.

X-ray magnetic scattering has also been applied to study the exotic behaviour of intermediate valence Ce alloys. These materials cannot be thought of as fully localised or band-like and represent a considerable challenge for understanding the complex magnetic structure and electronic properties. The new results show that valuable insight can be gained from X-ray scattering measurements, which complement neutron studies.

The determination of orbital magnetic moments in antiferromagnetic systems is mostly the domain of X-ray magnetic scattering; however, a new way of determining such moments has recently been demonstrated for CoO. The orbital moment was determined from spin-resolved photoemission measurements and opens up many new possibilities.

In ferromagnetic materials, X-ray magnetic circular dichroism (XMCD) has become an important tool in studying the relationship between magnetic anisotropy and orbital moments. A particularly striking example is presented for Nd2Fe14B at the spin-reorientation transition.

Significant progress has also been made in studying the magnetic properties of a new class of materials, magnetic multilayers. These materials have novel properties and are important for both basic and applied science. Using X-ray magnetic dichroism studies at both the Ni and Pt edges, it has been possible to provide a magnetic profile for these materials that can also be compared with theory.

X-ray magnetic dichroism is now an established field, however the general area of X-ray dichroism is much richer, with the possibility of observing a variety of different phenomena. One such example, related to optical activity, is the recent first observation of nonreciprocal X-ray gyrotropy.