Independence Day is celebrated on 4th of July of each year in the USA and it is the celebration of the day the United Sates Of America's declared it's independence from the control, ownership, and abuse of Great Britain (United Kingdom/Britain/England).
In essence, it is when USA was born and declared it's freedom from control and ownership of Great Britain. Independence Day is a federal holiday in the USA. Independence day is often referred to as "July 4th", or "4th Of July", but those phrases are not substitute names, and reference the date the holiday is celebrated.
In current times, Independence Day is commonly celebrated with lighting of fireworks or electronic light shows, music, and outdoor activities (picnics and games), the display of the "American" flag (USA flag), and the display of the USA flag colors red, white and blue.