  This paper is an experimental review of the study of processes with a single
top quark at the LHC. The pioneering times are over, and this is now a sector
of "precision physics" at colliders. Angular distributions of the decay
products of singly-produced top quarks are unique tests of the electroweak
interaction. Searches for rare final states of the form t+X (where X=$\gamma$,
Z, H) are very sensitive to new physics, and will enter with Run II in a very
interesting zone of the parameter space of some theories. The relative sign of
the Yukawa coupling of the top quark with respect to the Higgs coupling to
gauge bosons will be conclusively measured very soon in the tHq final state.
