Neutron stars—compact objects with masses similar to that of our Sun but radii comparable to the size of a city—contain the densest form of matter in the universe that can be probed in terrestrial laboratories as well as in earth- and space-based observatories. The historical detection of gravitational waves from a binary neutron star merger has opened the new era of multimessenger astronomy and has propelled neutron stars to the center of a variety of disciplines, such as astrophysics, general relativity, nuclear physics, and particle physics. The main input required to study the structure of neutron stars is the pressure support generated by its constituents against gravitational collapse. These include neutrons, protons, electrons, and perhaps even more exotic constituents. As such, nuclear physics plays a prominent role in elucidating the fascinating structure, dynamics, and composition of neutron stars.