  We present a perspective on the status of antiferromagnetism in
two-dimensional (2D) materials. Various types of spin-compensated orders are
discussed and include non-collinear order, spin spirals and altermagnetism.
Spin-orbit effects ultimately determine, whether compounds exhibit long range
order, Kosterlitz-Thouless physics, or multiferroic properties and we discuss
the basic magnetic prototypes that may arise in 2D materials depending on the
magnetic anisotropy and ordering vector. A summary of 2D antiferromagnets that
have been characterized experimentally is provided - with particular emphasis
on magnetic anisotropies and Neel temperatures. We then outline the ingredients
needed to describe the magnetic properties using density functional theory. In
particular, the systematic determination of magnetic ground states from the
generalized Bloch theorem and the magnetic force theorem, which may be used to
calculate magnetic excitations from the Heisenberg model with parameters
determined from first principles. The methods are exemplified by application to
the monolayer helimagnet NiBr$_2$. Finally, we present a summary of predicted
and prospective 2D antiferromagnets and discuss the challenges associated with
the prediction of N\'eel temperatures from first principles.
