  Topological magnetic textures have attracted considerable interest since they
exhibit new properties and might be useful in information technology. Magnetic
hopfions are three-dimensional (3D) spatial variations in the magnetization
with a non-trivial Hopf index. We find that in ferromagnetic materials, two
types of hopfions, Bloch-type and N\'{e}el-type hopfions, can be excited as
metastable states in the presence of bulk and interfacial Dzyaloshinskii-Moriya
interactions, respectively. We further investigate how hopfions can be driven
by currents via spin-transfer torques (STTs) and spin-Hall torques (SHTs).
Distinct from 2D ferromagnetic skyrmions, hopfions have a vanishing gyrovector.
Consequently, there are no undesirable Hall effects. N\'{e}el-type hopfions
move along the current direction via both STT and SHT, while Bloch-type
hopfions can be moved either transverse to the current direction by SHT or
parallel to the current direction by STT. Our findings open the door to
utilizing hopfions as information carriers.
