The ESA PLATO (PLAnetary Transits and Oscillations of stars) mission aims at the detection and characterisation (radii, mass, density, age) of terrestrial exoplanets in orbits up to the habitable zone around Sun-like stars. To achieve these goals, an optimised complementary Ground-based Observations Programme (GOP) is set up with the purpose to provide the spectroscopic, photometric and imaging observations needed to i) establish the true planet origin of the detected signal (vetting of false positives), and ii) accurately measure the mass of the transiting planets (with a goal of 10% precision), that are then combined with the precise radii and system age derived from the PLATO data.

The GOP is a fully integrated part of the PLATO mission. Its challenge is to optimally organise observations matching the target needs and determine the corresponding best observing strategy. It will involve the operation of instruments of various types and sensitivities, from small up to the largest telescopes. Participation to these observation activities is fully open to the ESA community and provides a unique opportunity to contribute to the success of the mission. We present here a summary of how the GOP is structured and operated, and provide information about how people can participate to the observational efforts, and what are the requirements and benefits for such a participation.