Latest QCD results in pp and PbPb collisions from ATLAS

The ATLAS experiment is measuring both pp and PbPb collisions at the largest energies available in laboratory delivered by the LHC accelerator. Tests of the Standard Model and searches for exotic phenomena require precise information on QCD processes, which are responsible for the background present in pp interactions. In the heavy ion collisions the QCD processes are determining the properties of the Quark-Gluon Plasma which is created in the conditions of the extreme energy density. In this contribution selected recent pp results from the ATLAS experiment are presented, including studies of jet properties and correlations in the multi-particle production. The effects of strong interactions in the dense matter created in PbPb collisions observed as the jet suppression and the collective flow are discussed in more detail.