Altermagnetism refers to the recent discovery of spin-split band structures that are anisotropic in momentum space in certain collinear compensated magnets. They have attracted much attention especially among people working on spintronics as they have the potential to provide a robust platform for antiferromagnetic spintronics. In this talk I will explain how altermagnetism arises as a direct consequence of symmetry and describe the order parameters and certain experimentally accessible features.