η_c as we know it

Various theoretical models for paracharmonium are critically reviewed. The main emphasis is put on the dispersion approach which has proved to be powerful enough to fix, say, the η_c mass, m_ηc=(3.00±0.02) GeV. A few original remarks concerning mainly the radiative transitions in charmonium are included. In particular, a new, simple, and reliable method for calculating Γ(J/ψ→η_cγ) is described which makes no reference to potentials, overlap integrals, etc.