Luminosity measurement with the ATLAS experiment at the LHC

Many physics measurements made by the ATLAS experiment at the LHC require a precise measurement of the integrated luminosity of the data sample. This talk will describe the ATLAS luminosity measurement for the full Run-2 dataset, including the absolute calibration of the luminosity scale using the van der Meer scan technique in dedicated LHC running, the extrapolation of this calibration to high-luminosity data-taking, and studies of the stability throughout the year. Prospects for further improvements with the Run-2 and later future datasets will also be discussed.