  The discovery of topological semimetals with multifold band crossings has
opened up a new and exciting frontier in the field of topological physics.
These materials exhibit large Chern numbers, leading to long double Fermi arcs
on their surfaces, which are protected by either crystal symmetries or
topological order. The impact of these multifold crossings extends beyond
surface science, as they are not constrained by the Poincar\'e classification
of quasiparticles and only need to respect the crystal symmetry of one of the
1651 magnetic space groups. Consequently, we observe the emergence of free
fermionic excitations in solid-state systems that have no high-energy
counterparts, protected by non-symmorphic symmetries. In this work, we review
the recent theoretical and experimental progress made in the field of multifold
topological semimetals. We begin with the theoretical prediction of the
so-called multifold fermions and discuss the subsequent discoveries of chiral
and magnetic topological semimetals. Several experiments that have realized
chiral semimetals in spectroscopic measurements are described, and we discuss
the future prospects of this field. These exciting developments have the
potential to deepen our understanding of the fundamental properties of quantum
matter and inspire new technological applications in the future.
