The Group of Seven, or simply G7, is a group of the world's most advanced economies.
To make things a little complicated, it has eight members ...but only seven are actually
countries.
They are: Canada, France, Germany, Italy, Japan, the US and the UK.
The European Union is the eighth member.
In the past the group has been known as the G6 and the G8, but they're seven since Russia
was suspended last year in response to the annexation of Crimea.
So what do they do?
Every year the leaders of the G7 nations hold a summit, to talk about the big issues of
the day.
This year that includes the situation in Ukraine, the environment, Greece, the Fifa corruption
scandal and the so-called Transatlantic
Trade and Investment Partnership, a major trade deal between the European Union and
the United States...
That's a lot to talk about in two days.. and of course, the leaders need to find the time to enjoy their surroundings!
This year's Summit is taking place at a former winter Olympics venue at the foot of Germany's
highest mountain, the Zugspitze.
Every year the summit attracts of big protests.
It's a mix of anti-capitalist protestors, who don't want to see a transatlantic trade
deal go ahead, and anti-war demonstrators.
The Germans have deployed no fewer than 17,000 police to guard the Summit venue.
And they will be busy.
The protests have largely been peaceful but there were some scuffles before the politicians
even arrived.
So what would make for a succesful summit?
Well with an agenda packed with such complex issues, it can be difficult to pinpoint tangible
results.
But for host Angela Merkel, it could set the groundwork for a broad agreement on limiting
climate change.
US President Obama will use the summit to help strengthen ties with Europe
- his relationship with the German Chancellor still recovering from the news last year that
the US National Security Agency had tapped her phone.
And Prime Minister David Cameron will be take the opportunity to put pressure on the European
Union to speed up the trade partnership with the
US.