With the standardization and commercialization completed at an unforeseen pace for 5th generation (5G) wireless networks, researchers, engineers and executives from the academia and industry have turned their attention to new candidate technologies that can support next generation wireless networks enabling more advanced capabilities in emerging scenarios. Explicitly, the 6th generation (6G) terrestrial wireless network aims to providing seamless connectivity not only to users but also to machine type devices for the next decade and beyond. This paper describes the progresses moving towards 6G, which is officially termed as ''international mobile telecommunications (IMT) for 2030 and beyond'' in the International Telecommunication Union Radiocommunication Sector (ITU-R). Specifically, the usage scenarios, their representative capabilities, the supporting technologies and spectrum are discussed, and research opportunities and challenges are highlighted.