The Agreement on Technical Barriers to Trade (TBT) requires that Members use as the basis of their technical regulations relevant international standards and that they play a full part in international standardizing bodies (ISBs). However, it fails to define the terms international standard and ISB. This poses a problem for regulators all over the world who need to decide which standards use as a basis of their technical regulations and standards and in which bodies play a full part. At the same time, some standardizing bodies have been de facto recognized as the global standardizers, even when there is a lack of understanding of their rules, their governance bodies and how they develop and adopt standards. This lack of understanding also creates a problem, because while these bodies have been provided with a quasi-regulatory power, this has not always been accompanied by transparency, inclusiveness or openness. This thesis has two main aims, first, propose a definition for the terms international standard and ISB and, second, to provide a holistic understanding of the international standardizing system, the ISBs and their processes, for which six ISBs, namely the CAC, the WP.7, the ISO, the IEC, the ASTM, and the FSC, are used as case studies. Using the two constructed definitions this thesis demonstrates that not all the bodies that are considered ISBs comply with the proposed definition and requirements of the TBT Agreement and that not all the standards adopted by ISBs are necessarily international standards according to the Agreement.