Simplify the following text for a Grade 8 native English-speaking person.
Original: The dominant forms of communism are based on Marxism , but non-Marxist versions of communism ( such as Christian communism and anarchist communism ) also exist .
Simplified: A red five-pointed star sometimes also stands for communism . The hammer and sickle is a well known symbol of communism and was on the flags of many countries that claimed to be building communism ( see top of article ) .