  The top quark is the heaviest of all known elementary particles. It was
discovered in 1995 by the CDF and D0 experiments at the Tevatron. With the
start of the LHC in 2009, an unprecedented wealth of measurements of the top
quark's production mechanisms and properties have been performed by the ATLAS
and CMS collaborations, most of these resulting in smaller uncertainties than
those achieved previously. At the same time, huge progress was made on the
theoretical side yielding significantly improved predictions up to
next-to-next-to-leading order in perturbative QCD. Due to the vast amount of
events containing top quarks, a variety of new measurements became feasible and
opened a new window to precisions tests of the Standard Model and to
contributions of new physics. In this review, originally written for a recent
book on the results of LHC Run 1, top-quark measurements obtained so far from
the LHC Run 1 are summarised and put in context with the current understanding
of the Standard Model.
