  Neutron reflectometry (NR) has emerged as a unique technique for the
investigation of structure and magnetism of thin films of both biologically
relevant and magnetic materials. The advantage of NR with respect to many other
surface-sensitive techniques is its sub-nanometer resolution that enables
structural characterizations at the molecular level. While in the case of
bio-relevant samples, NR can be used to probe thin films at buried interfaces,
non-destructively, even adopting a complex sample environment. Whereas the
polarized version of NR is best suited for revealing the interface magnetism
with a sub-nanometer depth resolution. In this article, I will briefly describe
the basic principle of NR with some applications of NR to both bio-relevant
samples and magnetic heterostructures.
