A successful description of hadron-hadron collision data demands a profound
understanding of quantum chromodynamics. Inevitably, the complexity of
strong-interaction phenomena requires the use of a large variety of theoretical
techniques -- from perturbative cross-section calculations up to the modelling
of exclusive hadronic final states. Together with the unprecedented precision
of the data provided by the experiments in the first running period of the LHC,
a solid foundation of hadron-hadron collision physics at the TeV scale could be
established that allowed the discovery of the Higgs boson and that is vital for
estimating the background in searches for new phenomena. This chapter on
studies of quantum chromodynamics at the LHC is part of a recent book on the
results of LHC Run 1 and presents the advances in theoretical methods
side-by-side with related key measurements in an integrated approach.Comment: 49 pages, 24 figures, To appear in "The Large Hadron Collider --
Harvest of Run 1", Thomas Sch\"orner-Sadenius (ed.), Springer, 2015 (532
pages, 253 figures; ISBN 978-3-319-15001-7, for more details, see
http://www.springer.com/de/book/9783319150000
