Press service is typically a department within an organization of some kind whose function is to communicate with mass media on topics related to that organization by issuing press releases and using other various means such as public speeches at news conferences, answering questions by telephone or on the Internet.
The main (or only) public figure who makes announcements is usually called a press secretary, press officer or spokesperson.
Popular way to distribute news from press service is through press releases that are sent to newspapers, related blogs and news aggregators, or by holding press conference.
Example of such an dedicated office is press service for the European Parliament.
See also