I visited Vietnam over the summer and I believe they are still under Communism. I dont know much about it though.
its the philosophical, social, political and economic ideology and movement whose ultimate goal is the establishment of the communist society, 
Are there a lot of countries under communism?
The goal is the establishment of socioeconomic order structured upon the common ownership of the means of production and the absence of social classes, money and the state.
I see. When was this ideology first conceived?
Communism includes a variety of schools of thought, which broadly include Marxism, anarchism ,a type of ideology
I had no idea it was that diverse. Has the concept been around for a long time?
Socialism
Socialism is a range of economic and social systems characterised by social ownership of the means of production and workers' self-management, as well as the political theories and movements associated with them. Social ownership can be public, collective or cooperative ownership, or citizen ownership of equity. There are many varieties of socialism and there is no single definition encapsulating all of them, with social ownership being the common element shared by its various forms.
Socialist systems are divided into non-market and market forms. Non
Communism
In political and social sciences, communism (from Latin "", "common, universal") is the philosophical, social, political, and economic ideology and movement whose ultimate goal is the establishment of the communist society, which is a socioeconomic order structured upon the common ownership of the means of production and the absence of social classes, money, and the state.
Communism includes a variety of schools of thought, which broadly include Marxism and anarchism (anarcho-communism), as well as the political