Soft QCD in ATLAS: Bridging non-perturbative and perturbative aspects of multiparticle production

We present the measurements of the inelastic and rapidity gap cross-sections, the underlying event with charged-particle jets, event shapes, transverse energy flow and different types of angular correlations in proton-proton collisions at centre-of-mass energies of s=0.9 and 7 TeV, performed with the ATLAS detector at the Large Hadron Collider at CERN. Predictions from various Monte Carlo models and theoretical calculations are compared to the data. The results lead to a deeper understanding of the interplay between soft and (semi)hard particle production processes.