Embracing the principles of network virtualization and digitization as a main pillar in the upcoming wireless generation has motivated the emergence of the digital twin (DT) paradigm as an enabler for 6G networks. The key concept of the DT technology is to create a digital replica of the physical components and functions of wireless networks, with the aim to realize ultra-reliable, low latency communication, while ensuring high energy-efficiency in resource-constrained networks. It is envisaged that DT will be the seed for the efficient deployment of intelligent, fully automated, zero-touch networks, in which artificial intelligence (AI) algorithms will be leveraged at the digital realm to enable virtualized network monitoring and operation. Despite its promising advantages, to reap the full potential of the DT technology in 6G networks, the cyber twin is envisaged to leverage AI algorithms, with novel data-driven paradigms, high performance computing, optimization theory, matching theory, as well as efficient cyber-physical interaction schemes, among others, to realize the necessary adaptation/reconfiguration at the physical twin with an imperceptible time-lag. In order to achieve the needed quality-of-service (QoS) for the successful implementation of a high-fidelity DT paradigm in 6G, a new level of stringent requirements pertaining to connectivity, reliability, latency, and data rate are imposed on future wireless generations. This Feature Topic (FT), which has attracted a large number of high-quality articles, aims to be a stepping-stone on advancing the research on DT for 6G, and to promote the development of high-fidelity Telecom Digital Twin.