The quest to probe the Standard Model more deeply and to search for physics beyond its current limits continues to drive the development of future particle colliders. Numerous ambitious proposals, both linear and circular designs, and lepton and hadron colliders, aim to push the frontiers of energy and luminosity to unprecedented levels. This seminar will present an overview of the main collider concepts, examining their scientific motivations, design strategies, and individual strengths. In addition, the technological challenges these proposed machines face will be discussed, along with potential synergies and complementarities among the different future collider proposals.