The Korean word for protest (or demonstration) is 시위. The word 항의 also means to protest, but it's a different meaning from the kind of protest where people gather and protest against something.

The above is all true. Both words mean "protest". Hwoever, given 시위 is where people physically gather together and protest against something which sometimes escalates into a riot, 항의 is the more appropriate term here as it covers the written sorts of protests...of the sort you would find on this site.

Almost all of the threads in this section are about the kind of protests where people physically gather together and protest against something - that's why I suggested the Korean title should be 시위.