More than eighty countries have formally joined the verbosely-titled Nice Agreement Concerning the International Classification of Goods and Services for the Purposes of Registration of Marks, concluded in 1957 and amended several times since. It obligates member countries to adopt and use the “international classification” system for classifying goods and services in a consistent way. The scheme has been so successful that many other jurisdictions have adopted the international classification system without joining the Nice Agreement. Accession to the Paris Convention for the Protection of Industrial Property is a prerequisite of Nice Agreement accession; for more on the Paris Convention, see our guide "What Is the Paris Convention?" A Committee of Experts periodically updates the classification; the most recent update went into force in 2012.
You can view a list of current Nice Agreement members on the World Intellectual Property Organization’s website here. For more details on the international classification system, please read our guide "What Is an International Class In a Trademark Application?"