Motivated by International Mobile Telecommunications (IMT)-2030, sixth generation (6G) mobile networks in 3GPP (third-generation partner project) commenced with a workshop in March 2025, attracting more than 200 contributions and 700 in-person attendances. While the details of 6G study and the eventual 6G specifications in 3GPP are yet to be developed, there is strong motivation in 3GPP to focus on the fundamental values that 6G may bring, most notably in terms of improving user experience and the overall network operation, particularly with respect to reducing the total cost of ownership (TCO). It is evident that there is a strong need to streamline and simplify the 6G specifications for efficient standardization, implementation, and commercial deployments. For the services also accommodated by the fifth generation (5G) networks, 6G is expected to provide meaningful enhancements. That is, instead of simply pushing for even higher envelopes such as peak data rates, more emphasis will be on improved coverage (especially at the cell edge and for certain data rates or services), and energy efficiency (for both end devices and networks) using the existing and new spectrum. Moreover, 6G is expected to support new services, with artificial intelligence (AI) and sensing as two primary examples. In this article, we provide a tutorial on the key technologies driving fundamental enhancements for the standardization of 6G and beyond, covering the necessary co-existence between 5G and 6G for smooth migration, AI-native radio access network (RAN), multiple-input-multiple-out (MIMO), sustainable operation with increased energy efficiency, coverage enhancements involving both terrestrial and non-terrestrial networks (NTN), integrated sensing and communication (ISAC), diverse device types including the low-end back-scattering based ambient internet of things (IoT) devices, and native support of NTN. We conclude this article by pointing out several key challenges and opportunities towards standardization of 6G and beyond.