Gatekeeping is the process of culling and crafting countless bits of information into the limited number of messages that reach people each day, and it is the center of the media’s role in modern public life. People rely on mediators to transform information about billions of events into a manageable subset of media messages. On the face of it, narrowing so many potential messages to so few seems to be impossible, but there is a lengthy and long-established process that makes it happen day in and day out. This process determines not only which information is selected, but also what the content and nature of messages, such as news, will be. Explaining such a powerful process is the purpose of this book, and a look at recent history demonstrates what is at stake.