G7 Hiroshima summit: Who's participating, what will be discussed?

Leaders of seven of the world's most powerful democracies are gathering for the Group of Seven summit in Hiroshima, the location of the world's first atomic attack at the end of World War II. From the emergence of crucial developing countries to security worries, including growing aggression from China, North Korea and Russia, here's a look at the G7, who will attend and some of the key issues: What is the G7 summit? The Group of Seven is an informal group of leading industrialized nations. It consists of Canada, France, Germany, Italy, Japan, the United Kingdom and the United States….