I start with a general exposition of altermagnetism. The 2D Lieb lattice model is the simplest case of this novel magnetic phase.  We will then focus on the anomalous Hall effect arising from the altermagnetic order and spin-orbit interaction. The Hall effect is forbidden by residual spin symmetries and becomes allowed in the magnetic group. I will sketch the details of the minimal model for the case of FeSb2. It is based on magnetic as well as spin space group formulations. We will discuss how the linear non-analytic scaling of the intrinsic Hall conductivity arises in a simple model. It originates from the singularity of the Berry curvature localized along lines on a Fermi surface confined to symmetry planes. These planes host spin degeneracy protected by spin symmetry, which is lifted by spin-orbit interaction. I will show how this gives rise to the non-analytic Hall conductivity.