Socialism advocates that the means of production, distribution, and exchange should be owned or regulated by the community as a whole. Pure socialism is the opposite of pure capitalism (trade and industry are controlled by private owners for profit, rather than by the state).
Most countries mix socialism and capitalism to a certain degree, even the US. There are a few service you do not want to be privatized such as law enforcement, defense, intelligence, judicial system, fire department. Can you imagine a country where the judicial system is a privately owned business, and which goal is to make a profit?