On behalf of the Steering Committee of the Complex Systems Society, αnd the Organizing Committee of CCS2020, I would like to invite you to attend and participate in CCS2020, to be organized online with the use of Zoom in the period December 7-11, 2020 and the young researchers CCS2020 Warm Up, in the period December 4-5, 2020. This Conference is in line with the series of meetings previously held in Singapore(2019), Thessaloniki, Greece(2018), Cancun, Mexico(2017), Amsterdam, Netherlands(2016), Tempe, Arizona,USA(2015), Lucca, Italy(2014), and more meetings in previous years. All these past meetings have delivered the highest quality of presentations, the most up-to-date findings, have been attended by the pioneers in the field of Complex Systems, as well by young aspiring students, numbering an attendance of close to one thousand. Our purpose is to deliver a well-tailored and focused event of the highest scientific and organizational standards, and for the first time in online mode. I am sure that we will all miss the warmth and cordiality that has been the tradition of past CCS meetings, but in view of the current world situation we are forced to this unprecedented step of meeting online. We all hope that next year we will return to the classical physical meetings that we all know. For the time being, let us all try to make the best out of it !