The ATLAS detector: status and performance in Run-II

During the first extended shutdown of the LHC, in 2013 and 2014, the ATLAS detector has undergone several improvements. A new silicon pixel detector layer has been added inside of the existing layers, enhancing vertex identification, while the coverage of the muon detector has been significantly expanded. Many other detector systems have been upgraded to handle the higher expected pileup conditions in the coming years and to generally improve their performance. This document describes these upgrades and the resulting impact on the identification and performance of standard physics objects. Preliminary results using the first $\sim80\,\mathrm{pb}^{-1}$ of 2015 data at $\sqrt{s}=13\,\mathrm{TeV}$ are presented, demonstrating the capability of ATLAS to perform both searches and measurements.