Please help me.. what is NATO?

Other answers explain that it was the North Atlantic Treaty Organisation. It was set up when the Communist Soviet Union base in Russia started knocking off the eastern european states, one by one, from 1946 onwards. It was there to protect the free nations of Europe with the backing of the USA. Russia have never forgiven the USA for spoiling its aims and they use still use every opportunity to castigate the USA, some of which appears in the ranting in some of the Yahoo questions.