Leaders of the world's largest economies have reached an agreement to tackle the global financial crisis with measures worth $1 trillion (£681bn).
To help countries with troubled economies, the International Monetary Fund (IMF) will get extra resources worth up to $750bn.
There will also be sanctions against secretive tax havens and tougher global financial regulation.
And the G20 has committed about $250bn to boost global trade.
On behalf of the G20, Prime Minister Gordon Brown announced the following steps:
Bankers' pay and bonuses will be subject to stricter controls
A new Financial Stability Board will be set up to work with the IMF to ensure co-operation across borders and provide an early warning mechanism for the financial system
There will be greater regulation of hedge funds and credit ratings agencies
A common approach to cleaning up banks' toxic assets has been agreed
The world's poorest countries will receive $50bn in aid.
The IMF has been one of the biggest beneficiaries of the G20 summit.
The resources it has to help troubled economies will be increased to $500bn.
An overdraft facility will also be increased to $250bn (in the IMF's currency, so-called Special Drawing Rights) that the world's poorest countries can call on.
"This is the day that the world came together to fight back against the global recession, not with words, but with a plan for global recovery and for reform and with a clear timetable for its delivery," Mr Brown said.