  Flavour-changing neutral-current processes, such as $b\to s \ell^+\ell^-$,
are forbidden at tree level in the Standard Model and hence might receive
comparatively large corrections from new particles. This document highlights
recent measurements from LHCb on $b\to s \ell^+\ell^-$ and purely-leptonic
decays, including tests of lepton flavour universality and searches for lepton
flavour violation.
