  Skyrmions are topologically stable quasiparticles that have been predicted
and demonstrated in quantum fields, solid-state physics, and magnetic
materials, but only recently observed in electromagnetic fields, triggering
fast expanding research across different spectral ranges and applications. Here
we review the recent advances in optical skyrmions within a unified framework.
Starting from fundamental theories, including classification of skyrmionic
states, we describe generation and topological control of different kinds of
optical skyrmions in structured and time-dependent optical fields. We further
highlight generalized classes of optical topological quasiparticles beyond
skyrmions and outline the emerging applications, future trends, and open
challenges. A complex vectorial field structure of optical quasiparticles with
versatile topological characteristics emerges as an important feature in modern
spin-optics, imaging and metrology, optical forces, structured light and
topological and quantum technologies.
