  This is a pedagogical introduction to the physics of confinement on $R^3
\times S^1$, using $SU(2)$ Yang-Mills with massive or massless adjoint fermions
as the prime example; at the end, we also add fundamental flavours. The
small-$S^1$ limit is remarkable, allowing for controlled semiclassical
determination of the nonperturbative physics in these, mostly
non-supersymmetric, theories. We begin by reviewing the Polyakov confinement
mechanism on $R^3$. Moving on to $R^3 \times S^1$, we show how introducing
adjoint fermions stabilizes center symmetry, leading to abelianization and
semiclassical calculability. We explain how monopole-instantons and twisted
monopole-instantons arise. We describe the role of various novel topological
excitations in extending Polyakov's confinement to the locally four-dimensional
case, discuss the nature of the confining string, and the $\theta$-angle
dependence.~We study the global symmetry realization and, when available,
present evidence for the absence of phase transitions as a function of the
$S^1$ size. As our aim is not to cover all work on the subject, but to prepare
the interested reader for its study, we also include brief descriptions of
topics not covered in detail: the necessity for analytic continuation of path
integrals, the study of more general theories, and the 't Hooft anomalies
involving higher-form symmetries.

High Energy Physics - Theory;High Energy Physics - Lattice;High Energy Physics - Phenomenology