  Studies on small-scale jets' formation, propagation, evolution, and role,
such as type I and II spicules, mottles, and fibrils in the lower solar
atmosphere's energetic balance, have progressed tremendously thanks to the
combination of detailed observations and sophisticated mathematical modelling.
This review provides a survey of the current understanding of jets, their
formation in the solar lower atmosphere, and their evolution from
observational, numerical, and theoretical perspectives. First, we review some
results to describe the jet properties, acquired numerically, analytically and
through high-spatial and temporal resolution observations. Further on, we
discuss the role of hydrodynamic and magnetohydrodynamic instabilities, namely
Rayleigh-Taylor and Kelvin-Helmholtz instabilities, in jet evolution and their
role in the energy transport through the solar atmosphere in fully and
partially ionised plasmas. Finally, we discuss several mechanisms of
magnetohydrodynamic wave generation, propagation, and energy transport in the
context of small-scale solar jets in detail. This review identifies several
gaps in the understanding of small-scale solar jets and some misalignments
between the observational studies and knowledge acquired through theoretical
studies and numerical modelling. It is to be expected that these gaps will be
closed with the advent of high-resolution observational instruments, such as
Daniel K. Inouye Solar Telescope, Solar Orbiter, Parker Solar Probe, and Solar
CubeSats for Linked Imaging Spectropolarimetry, combined with further
theoretical and computational developments.
