Global Fits of Parton distributions

Abstract

I discuss recent developments in the determination of parton distributions from global fits. I concentrate on the errors associated with these parton distributions and with the physical quantities which are determined in terms of them. I outline the various techniques used to quantify the uncertainties due to errors on experimental data used in the fits, and provide a number of examples of predictions with their uncertainties. However, I demonstrate that this source of errors may, in some circumstances, be less important than errors due to underlying assumptions in the fitting procedure and due to the incomplete nature of the theoretical framework currently employed.