As long as a country isn't at war, usually:
United States
Japan
Korea (South)
China
Russia
Austrailia
Italy
Greece
England
France
Germany
Spain
Belgium
Norway
Finland
Netherlands (Holland)
Denmark
Swden
Canada
Mexico
Brazil
Jamaica
and some more go, but not every year.
80 countries and 2 territories participated in the 2010 Winter Olympic Games in Vancouver, Canada. More countries compete in the Summer Olympics than Winter.
Yes, you can compete in consecutive Olympic games.
You have to pass your country's national trials.
No
Europe had the most countries competing in the 2010 Olympics with 49 of its 51 countries competing. Kosovo does not compete as it has only claimed independence in 2008 and has yet to be fully recognized. The Vatican does not have a National Committee for the Olympic Games and thus does not compete.
The Olympic Games that allowed professional athletes to compete were the Summer Olympics starting in 1984 and the Winter Olympics starting in 1992.
Viktor Balck (not Black) was a member of the International Olympic Committee at the time the Olympic Winter Games were first held in 1924, but he did not compete as an athlete.
4-man bobsled
The Olympic Ideal is the premise that individuals, not countries, compete against each other in sport and through these these competitions held every 4 years for both summer and winter Olympics, peaceful competition without the burden of politics, religion, or racism.
The Snow Leopard
3
Countries do not enter the Olympic Games. The Olympic Movement consists of international sports federations (IFs), National Olympic Committees (NOCs), and organizing committees for each specific Olympic Games.