Answer:
Well there is a lot of stuff, but I am probaly going to miss a lot of things.
-They all have been in a war before
-They have a form of goverment
-They all have the letter "A" in their names :)
-They have a population of 500,000+
-They have a language for their country
-They have people who live in their countries
-They have borders
-They have landmasses that they own
-They import and export items
-They are all on the planet Earth :)