You can choose who can comment and view comments on your articles. The two main groups are everyone and only logged in readers and users.
Enable comments turns on comments. Comments will appear where you place the comment merge code in your article HTML (Settings > Style > Custom HTML > Article): [template("comments")]
Restrict commenters only allows users and readers who are logged in to your knowledge base to leave comments. Readers or users who are not logged in can still see comments.
Restrict visibility only allows users and readers who are logged in to your knowledge base to view comments. People not logged in will not see comments at all.