As of 2014, there are no countries that have pure socialism, which is actually an economic system and not a form of government. The former Soviet Union is the best example of true socialism, while China, North Korea and Cuba are the three modern countries with the most socialist economies.
The economies of Cuba, China and North Korea are mostly government controlled, which is one of the primary components of the socialist system. The degree of government economic control varies in these three countries. For instance, China is slowly allowing more privately owned businesses as they transition from a socialist economy to a social market economy. Cuba has also been moving more towards a mixed economy since President Raul Castro introduced a series of economic reforms in 2010. Neither Cuba or North Korea have a stock exchange, which is another key component of pure socialism.
Although there are no true socialist countries, the principles of socialism are still applied to various aspects of different countries, such as health care or public education. Both North Korea and Cuba have extensive social programs such as these, as does Sweden and many other European countries. However, just because a country offers social benefits to its citizens doesn't make it socialist.