  Designing microscopic and nanoscopic self-propelled particles and
characterising their motion has become a major scientific challenge over the
past decades. To this purpose, phoretic effects, namely propulsion mechanisms
relying on local field gradients, have been the focus of many theoretical and
experimental studies. In this review, we adopt a tutorial approach to present
the basic physical mechanisms at stake in phoretic motion, and describe the
different experimental works that lead to the fabrication of active particles
based on this principle. We also present the collective effects observed in
assemblies of interacting active colloids, and the theoretical tools that have
been used to describe phoretic and hydrodynamic interactions.
