The Independence Day Act, 1947, is an Act of the Parliament of the United Kingdom that partitioned British India into two new independent dominions- India and Pakistan.

The Act received Royal Assent on July 18, 1947, and thus India and Pakistan, comprising West (modern-day Pakistan) and East (modern-day Bangladesh) regions, came into being on August 14.

These dominions separated the Muslim, Hindu and Sikh populations and caused the biggest forced migration that has ever happened that was not the result of war or famine.
The Act repealed the use of ‘Emperor of India’ as a title for the British Crown and ended all existing treaties with the princely states.

Lord Mountbatten continued as the Governor-General and Jawaharlal Nehru was appointed India’s first Prime Minister, Muhammad Ali Jinnah became Pakistan’s Governor-General and Liaquat Ali Khan became the country’s first Prime Minister.
Since then, August 15, and August 14 is celebrated as the Independence Day of India and Pakistan respectively.