PCT - The Patent Cooperation Treaty (PCT) provides a unified procedure for filing patent applications to protect inventions internationally in all signatory countries. A majority of the world's countries are signatories to the PCT. A single patent filing results in an “international application” for which a single search is conducted, accompanied by a written opinion (and optionally a preliminary examination), after which the examination (if provided by national law) and grant procedures are handled by the relevant national or regional authorities. The PCT does not lead to the grant of an "international patent", which does not exist.