The Tile Calorimeter (TileCal) of the ATLAS experiment at the LHC is the central hadronic calorimeter
designed for energy reconstruction of hadrons, jets, tau-particles and missing transverse energy. TileCal
is a scintillator-steel sampling calorimeter and it covers the region of pseudorapidity < 1.7.
The scintillation light produced in the scintillator tiles is transmitted to photomultiplier tubes (PMTs). Signals from the PMTs are amplified, shaped and digitized by
sampling the signal every 25 ns. Each stage of the signal production from scintillation light to the signal reconstruction is monitored and calibrated.
Results on the calorimeter operation and performance are presented, including the calibration, stability,
absolute energy scale, uniformity and time resolution. These results show that the TileCal performance
is within the design requirements and has given essential contribution to reconstructed objects
and physics results.