After blocking a person on Facebook, neither party is able to view the other person's past or future postings, nor send correspondences to one another via chat or private message. Facebook profiles are no longer visible to or searchable by those who are blocked.
As of 2014, in order to block a person on Facebook, go to the Privacy Settings located in the General Settings. Located in the lower section of the page, find the portion labeled Blocked People. Locate the Person box, and type in the name of the person to block. Once the name is identified by Facebook, select the person desired, and click Block to prevent continued communication.