PT Journal AU ATLAS Collaboration (Aad, Gea Alvarez Piqueras, D Aparisi Pozo, JA Bailey, AJ Cabrera Urban, S Castillo, FL Castillo Gimenez, V Cerda Alberich, L Costa, MJ Escobar, C Estrada Pastor, O Ferrer, A Fiorini, L Fullana Torregrosa, E Fuster, J Garcia, C Garcia Navarro, JE Gonzalez de la Hoz, S Gonzalvo Rodriguez, GR Guerrero Rojas, JG Higon-Rodriguez, E Lacasta, C Lozano Bahilo, JJ Madaffari, D Mamuzic, J Marti-Garcia, S Melini, D MiƱano, M Mitsou, VA Rodriguez Bosca, S Rodriguez Rodriguez, D Ruiz-Martinez, A Salt, J Santra, A Soldevila, U Sanchez, J Valero, A Valls Ferrer, JA Vos, M TI Electron and photon performance measurements with the ATLAS detector using the 2015-2017 LHC proton-proton collision data SO Journal of Instrumentation JI J. Instrum. PY 2019 BP P12006 - 69pp VL 14 DI 10.1088/1748-0221/14/12/P12006 LA English DE Particle identification methods; Performance of High Energy Physics Detectors AB This paper describes the reconstruction of electrons and photons with the ATLAS detector, employed for measurements and searches exploiting the complete LHC Run 2 dataset. An improved energy clustering algorithm is introduced, and its implications for the measurement and identification of prompt electrons and photons are discussed in detail. Corrections and calibrations that affect performance, including energy calibration, identification and isolation efficiencies, and the measurement of the charge of reconstructed electron candidates are determined using up to 81 fb(-1) of proton-proton collision data collected at root s = 13 TeV between 2015 and 2017. ER