Formed in 1949 with the signing of the Washington Treaty, NATO is a security alliance of 30 countries from North America and Europe. Its main goal is to safeguard the Allies' freedom and security by political and military means. Its full form is North Atlantic Treaty Organization.

On April 4th, 2023, Finland became the 31st ally of NATO. Finland's President Sauli Niinistö at the time said his country sought NATO membership because Russia's invasion proved that the Kremlin (which is a fortified complex in the center of Moscow) does not respect officially non-aligned countries, which are countries who do not want to be officially aligned with or against any major power. On 4th April, 2023, Finland's flag was raised alongside those of the 30 other nations in the alliance during a ceremony at NATO headquarters in Brussels.

To know more about this, please check:

https://www.youtube.com/watch?v=6B-6ybN_yLY