The end of year 2021 marked the 10^th anniversary of the enactment of EU Regulation No. 1227/2011 of the European Parliament and of the Council of 25 October 2011 on wholesale energy market integrity and transparency (hereafter “REMIT” or “the Regulation”). On this occasion, the 5^th REMIT Forum was organized as a series of virtual events on 25, 26 and 28 October 2021 (“2021 REMIT Forum”). The introductory webinar to REMIT and the main plenary session were followed by special interest groups sessions on data, reporting and technology as well as on the 6^th Edition of ACER Guidance on the application of REMIT (“ACER Guidance”). Conclusions of the 2021 REMIT Forum will be revealed in different contexts throughout our own series of articles aimed at marking the occasion.