What is the White House press pool and why is it in a row with Trump?

The latest row began on Friday, when Trump said he was banning three outlets - CNN, Politico and MS NOW - from the White House, accusing them of spreading "fake news" and "fictions and lies" about his team.A day later, reporters from those organisations found that their entry badges to the White House had been disabled.On Monday, all the major US TV networks decided to pull out of White House pool duties - in effect boycotting presidential events.That afternoon came the first test of this post-pool era - the new helipad. But with no pool cameras present, much of the media did not carry any pictures and for those that did, there was no microphone to clearly pick up the president's remarks.EPAThe TV network rotate coverage of White House eventsWhy did US networks pull out of filming Trump?Fox News Washington bureau chief Bryan Boughton, who currently holds the rotating role covering the White House, wrote in an email seen by the BBC that "effective today, the TV pool will not be covering events designated as pool coverage" of President Trump.In a joint statement, the five networks said: "The public has a vital interest in receiving accurate, independent information about its government.