Experimental Review of Photon Structure Function Data

The present knowledge of the structure of the photon is presented based on results obtained by measurements of photon structure functions at e+e- collider. Results are presented both for the QED structure of the photon as well as for the hadronic structure, where the data are also compared to recent parametrisations of the hadronic structure function F2gamma(x,Q^2). Prospects of future photon structure function measurements, especially at an International Linear Collider are outlined.