Recently the muon collider has been recognised as an important option to be considered for the future of particle physics.
It is part of the European Accelerator R&D Roadmap developed in 2021 and approved by Council. Also interest is rising in the Amerikas and in Asia, for example demonstrated by the ongoing Snowmass process.
The paper will give an introduction into the muon collider concept and the identified challenges. It will also describe the R\&D progress and plans.