What do you mean by the Non-Cooperation Movement?

Hint: The Non-Cooperation movement was launched against the Rowlatt Act of 1919. The means of protest in this movement were of Ahimsa or non-violence as practised by Gandhi and the movement ended because of an act of violence in Chauri Chaura.

Complete answer: The Non-Cooperation movement dates between 1920-22 and was led by Mahatma Gandhi and his model of Satyagrah was applied here. This movement literally meant not cooperating with the British government and therefore, acted as a resistant move against the colonial powers.
Though the non-cooperation movement was started with the background of opposing the measures taken by the British Crown in the Rowlatt Act of 1919 and the massacre at the Jallianwala Bagh, it was also a strategic move to unite the Hindus and Muslims. Gandhi Ji supported the Khilafat Movement which was being led against the removal of Khalifa, who was the political head of the Muslims, after the defeat of the Ottoman Empire in World War I. In this movement, Indians gave up titles under the British government, opposed all government institutions, opposed English education, gave up foreign goods and refused to pay taxes.
This was a very strong campaign and saw a united effort from all over India. But in 1922, at Chauri Chaura in Bihar, a group of protestors burnt a police station which led to the death of 22 police officers. This led to Mahatma Gandhi calling off the movement.

Note: This movement was the first time when the demand for self-governance arose among Indian masses. The Indian National Congress had withdrawn its support from the policies of the British government and demanded independence.