The PCT procedure includes two main phases, the international phase and national phase
Filing: Firstly, you need to file an international application with a national or regional patent Office or WIPO, complying with the PCT formality requirements, in one language, and you pay one set of fees.
International Search: an “International Searching Authority” (ISA) (one of the world’s major patent Offices) identifies the published patent documents and technical literature (“prior art”) which may have an influence on whether your invention is patentable, and establishes a written opinion on your invention’s potential patentability.
International Publication: as soon as possible after the expiration of 18 months from the earliest filing date, the content of your international application is disclosed to the world.
Supplementary International Search (optional): a second ISA identifies, at your request, published documents which may not have been found by the first ISA which carried out the main search because of the diversity of prior art in different languages and different technical fields.
International Preliminary Examination (optional): one of the ISAs at your request, carries out an additional patentability analysis, usually on an amended version of your application.
National Phase: after the end of the PCT procedure, usually at 30 months from the earliest filing date of your initial application, from which you claim priority, you start to pursue the grant of your patents directly before the national (or regional) patent Offices of the countries in which you want to obtain them.