Vatican City, the world's smallest country, established in 1929 via the Lateran Treaty, is a sovereign ecclesiastical state governed by the Pope, 

Monaco, the world's second-smallest country, is a luxurious resort nation on the French Riviera, famous for Monte Carlo, its casino, and beaches, with a population of around 31,813.

Nauru, the world's smallest island country, is an 8.5-square-mile nation in the South Pacific with a population of around 10,000, having gained independence from Australia in 1968.

Tuvalu, a small Pacific island nation of nine coral atolls, relies on rainwater collection and storage due to a lack of freshwater sources, including rivers, streams, and drinkable groundwater.

San Marino, a landlocked microstate surrounded by Italy, claims to be Europe's oldest state, founded in the 4th century, with a population of around 35,000 on Mt. Titano.

Liechtenstein, a microstate nestled in the Alps between Switzerland and Austria, is a doubly landlocked country with an area of 62 square miles and a population of 40,272.

The Marshall Islands, the world's seventh-smallest country, comprises 29 coral atolls and five main islands, spanning 750,000 square miles near the equator in the Pacific Ocean.