An Experimental Review of Charmonium

This review briefly outlines recent experimental results from the charmonium system. These include new measurements of the M1 radiative transition rates $B(\psi (1S,2S)\to \gamma {\eta }_c(1S))$; new insights into the mass of the ${\eta }_c(1S)$; the observation of $J\mathrm{/}\psi (1S)$ decays to three photons; new measurements of the two-photon widths of the ${\chi }_{cJ}(1P)$; the observation of radiative decays of the ${\chi }_{cj}(1P)$ to light quarks; a precise measurement of the $h_c(1P)$ mass; and an update on properties of the ${\eta }_c(2S)$. Each result adds piecemeal to our understanding of the strong force.