  These notes summarise the lectures I gave during the summer school
"International Scientific Meeting on Nuclear Physics" at La R\'abida in Spain
in June 2018. They offer an introduction to nuclear-reaction theory, starting
with the basics in quantum scattering theory followed by the main models used
to describe breakup reactions: the Continuum Discretised Coupled Channel method
(CDCC),the Time-Dependent approach (TD) and the eikonal approximation. These
models are illustrated on the study of the exotic structure of halo nuclei.
