The biggest country in the world is Russia; even after the collapse of the Soviet Union in 1991. It is over 17 million square kilometers and has approximately 142 million people; to give you an idea of what that means; almost 2 whole countries the size of the United States could fit within the borders of Russia.
The Soviet Union was very much larger and used to include Armenia, Azerbaijan, Belarus, Estonia, Georgia, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Moldova, Tajikistan, Turkmenistan, Ukraine, and Uzbekistan.
Canada is the second biggest country in the world with approximately 9.9 million square kilometers and only 33 million people for all that space!
The United States of American comes in at a close third with 9.6 million square kilometers and over 304 million people.
The biggest country in the world by population is China with 1.3 billion people, but it is the 4th largest by land area, close in size to the United States at 9.5 million square kilometers.