The Brics group of countries is due to take in five new member states, from Africa and the Middle East.
The organisation wants a greater say for emerging economies.
What does Brics mean and who are the new members?
In 2006, Brazil, Russia, India and China created the "Bric" group. South Africa joined in 2010, making it "Brics".
Egypt, Ethiopia, Iran, Saudi Arabia and the United Arab Emirates are due to enter on 1 January.
No name for the expanded group has been announced, but it is thought it might be "Brics +".
Argentina was invited to join but its new president, Javier Milei, has said it will not.
Brics countries make decisions at an annual summit. Members of the group take turns to be its president for a year.
Why does Brics matter?
Brics countries include major world powers, such as China and Russia, and countries which are major powers on their continent, such as South Africa and Brazil.
The expanded group has a combined population of about 3.5 billion, or 45% of the world's population.
Its combined economy is worth over $28.5tn - about 28% of the global economy.
Brics countries will also be producing about 44% of the world's crude oil.
However, Brics countries say that Western nations dominate important bodies such as the International Monetary Fund and the World Bank, which lend money to countries.
They have called for a "greater voice and representation" for emerging economies.
In 2014, the Brics nations set up the New Development Bank to lend money for development.
By the end of 2022, it had lent nearly $32bn to emerging nations for new roads, bridges, railways and water supply projects.
This is China's main aim for Brics, says Prof Padraig Carmody, an expert in development geography at Trinity College Dublin.
"Through Brics, China is trying to grow its power and influence - especially in Africa," he says. "It wants to be be the leading voice for the Global South."
Russia, the other major world power in Brics, has a different purpose for it.
"Russia sees it as part of its fight against the West, helping it to overcome the sanctions imposed after the invasion of Ukraine," says Creon Butler of the London-based think tank Chatham House.
Iran's membership could increase the anti-Western nature of Brics, he adds.
Will a Brics currency replace the dollar?
Nations often use the US dollar to trade between themselves.
Leading politicians in Brazil and Russia have suggested creating a Brics currency, to reduce its dominance. However, this was not discussed at its 2023 summit.
It would be impractical for Brics nations to create a common currency because their economies are so different, says Professor Carmody.
However, "they may consider in the future creating some new currency to be used for international trade payments, or a cryptocurrency for international trade," he says.
Is Brics a rival to the G20?
The G20 group was set up in 1999 for developed and developing nations to discuss global problems, such as financial crises and climate change.
However, the Brics group contains many of the countries which are in the G20.
In future, they may work in tandem, says Dr Irene Mia from the International Institute for Strategic Studies, a think tank.
"Together, they might push for more money for developing nations to tackle climate change, or to reduce the power of the US dollar as the world's currency," she says.
How will Russia use its 2024 Brics presidency?
Russia will host the Brics summit in Kazan in October.
Vladimir Putin has said he will use the presidency to:
- increase the role of Brics in the international financial system
- develop cooperation between banks and expand the use of Brics currencies
- promote collaboration between tax and customs authorities
"With Brics, Russia will want to show the West that it still has friends and allies in the rest of the world, despite its invasion of Ukraine," says Dr Mia.
