if you are interested, there is even better word: 공산주의 - communism. Or the absolute socio-political gamebreaker, 주체사상 - the Juche idea
It can be compared to English's -ism. Capitalism = 자본주의 (資本主義, capital 자본, ism 주의)
I saw in the next lesson that the word for socialism is related to the word for society.
So 의 is a diphthong (strong 으+[j]) at the beginning of a word, sounds like 에 for the possessive particle and sounds like 이 when part of a word that isn't at the beginning? Is that a good summary?