Permafrost is recognized as an Essential Climate Variable (ECV) within the Global Climate Observing System (GCOS) of the World Meteorological Organization (WMO). The Global Terrestrial Network for Permafrost (GTN-P) is the primary international programme concerned with the long-term monitoring of permafrost. The core mission of the GTN-P is a sustained comprehensive long-term monitoring network to provide consistent, representative and high-quality long-term data series of indicator variables (ECV products) at globally distributed key sites and to assess the state and changes of permafrost over time. The GTN-P Strategy and Implementation Plan (SIP) 2021-2024 describes the governance and management structure of GTN-P, linkages to regional and global observing systems, the management process and reporting strategies. It presents measurement methods and protocols used for field data collection and the GTN-P data management system, which are designed to collect, process, analyse, and visualize permafrost data to feed into (support) synthesize studies from local to global scales and Earth System Models targeting climate feedbacks on the terrestrial cryosphere. The GTN-P SIP concludes by outlining potential future developments of the network, which are needed to sustain and succeed its core missions of providing high-quality permafrost data, serving as a sustainable long-term data archive and remain a forum for the GTN-P community.