A moment in history
It was a simple gesture that lasted just seconds but will go down in history.
Her Majesty the Queen has met Martin McGuiness, a senior Sinn Fein politician who was once a commander of the IRA, and they shook hands.
It's being seen by many as the ultimate act of reconciliation. More than three and a half thousand people died in the troubles in Northern Ireland including the Queen's cousin Lord Mountbatten.