Permanent establishment defined by fixed place, agent authority, and exclusions for preparatory or auxiliary activities. Permanent establishment is a fixed place of business through which an enterprise carries on business, including management, branches, offices, workshops, storage facilities for others, agricultural sites, sales outlets, long-term construction or installation projects, and installations for natural resource exploration or exploitation. Exclusions cover facilities used solely for storage, display, processing by others, purchasing, information collection, and preparatory or auxiliary activities. Agency rules treat persons habitually concluding contracts or maintaining stock for delivery as creating a permanent establishment, while independent agents and mere control between related companies do not automatically create one.