IEC TS 62600-101:2024 establishes a system for estimating, analysing and reporting the wave energy resource at sites potentially suitable for the installation of Wave Energy Converters (WECs). This document is to be applied at all stages of site assessment, from initial investigations to detailed project design. This document is to be applied in conjunction with the IEC Technical Specification on WEC performance (IEC TS 62600-100) to estimate the mean annual energy production of a WEC or WEC array as described in the methodology in Annex A. This document is not intended for estimation of extreme wave conditions. The framework and methodologies prescribed in this document are intended to ensure that only adequate models are used, and that they are applied in an appropriate manner to ensure confidence and consistency in the reported results. Moreover, the document prescribes methods for analysing metocean data (including the data generated by modelling) in order to properly quantify and characterize the temporal and spatial attributes of the wave energy resource, and for reporting the results of a resource assessment in a comprehensive and consistent manner.