Ultracold neutrons (UCNs) can be confined and manipulated in traps and are an excellent probe to study fundamental symmetries and interactions. Storage lifetimes of several hundred seconds enable high-precision experiments with impact on astrophysics and cosmology, complementary to high-energy physics. Although longstanding, the search for a non-vanishing electric dipole moment of the neutron is currently a hot topic pursued by many research groups around the world. A non-zero result would provide evidence of CP violation beyond the CKM mechanism of the standard model of particle physics and help understanding the asymmetry of baryonic matter and antimatter in the universe. The neutron lifetime is a second key observable investigated with ultracold neutrons. It determines the primordial abundances of the light chemical elements after the big bang and is still astonishingly poorly known. A third example of current studies covered in this talk is a search for deviations from Newton’s gravity law at distances in the micrometre range, using spectroscopy of quantum states of the neutron confined by a horizontal mirror and gravity. A major step forward in experimental accuracies is expected from the availability of advanced UCN sources, such as currently being developed at the ILL in Grenoble and based on superfluid helium as a converter medium.