Fascism: a governmental system led by a dictator having complete power, forcibly suppressing opposition and criticism, regimenting all industry, commerce, etc., and emphasizing an aggressive nationalism and often racism.
Communism: a system of social organization in which all economic and social activity is controlled by a totalitarian state dominated by a single and self-perpetuating political party.
Socialism: a theory or system of social organization that advocates the vesting of the ownership and control of the means of production and distribution, of capital, land, etc., in the community as a whole.
*Special note: These three are not the same. That means you can't just interchange them whenever you feel like it.
Thank you and have a nice day.