Is it true that the patent obtained in a country is valid all over the world?

A patent is only legally valid within the country in which it is registered.

If you want to obtain a patent in other countries, it is essential to apply separately to those countries. However, the people who set up the intellectual property system in the world thought that it would be very costly to apply separately to each country. Therefore, they have introduced PCT, the International Patent Application System, through WIPO, the World Intellectual Property Organization. In this way, the inventor makes a PCT application and applies to each member of the PCT at the same time.

The number of member countries in PCT, which is an International Application System, is 152 as of 2019.