The seven emirates are Abu Dhabi, Dubai, Sharjah, Ajman, Umm Al-Quwain, Ras Al Khaimah and Fujairah. Each one still has its own ruler, called a sheikh, and its own special character - different beaches, different mountains, different markets. But they share one flag, one passport, one football team.
Abu Dhabi is the biggest emirate by far. It is also the capital, where the president lives and where the government meets. Dubai is the most famous to people in other countries because of its skyscrapers and airport. The smaller emirates are quieter, with palm farms, fishing villages and old forts on hilltops.
The flag has four colours, and each one stands for something. Red is for bravery. Green is for the land's gardens. White is for peace. Black is for the strength of the people. The colours come from a poem written hundreds of years ago.
Joining seven emirates into one country was the idea of Sheikh Zayed bin Sultan Al Nahyan. He believed they would be stronger together than apart - like fingers on a hand. The UAE celebrates its birthday every year on 2 December, the day the union began.