What’s the White House press pool?

The Justice Department’s decision to investigate the five TV networks that make up the White House television pool for potentially violating antitrust laws has thrust the decades-old press pool system into the spotlight.

While the Justice Department investigates, the three news outlets CNN, MS NOW and Politico are challenging the Trump policy in federal court, in a case with implications for the longstanding system that journalists in the U.S. and around the world rely on to report on the presidency.