Google is your friend:

http://www.catholicnews.com/data/stories/cns/1200298.htm

World Communications Day is about the use of mass media communications. This is a subject that has been the focus of attention from the Church since a decree was devoted to it by Vatican II in 1963. In church lingo, it's about "the means of social communication". Back then the term related to the press and broadcasting, but now it includes the internet.