Theresa May will be attending her last major gathering of world leaders at the G20 summit in Osaka.

– What is the G20?

It is a summit bringing together the leaders of 19 major powers and the European Union.

The gathering is formally known as the “summit on financial markets and world economy” and its members represent more than 80% of global GDP.

The meeting takes place on Friday and Saturday.

– Which countries attend?

Argentina, Australia, Brazil, Canada, China, France, Germany, India, Indonesia, Italy, Japan, Mexico, South Korea, South Africa, Russia, Saudi Arabia, Turkey, UK and the USA.

At the Osaka summit they will be joined by leaders from guest nations the Netherlands, Singapore, Spain, Vietnam and Thailand in its role as the president of trade bloc Asean, Egypt in its role as African Union president and Chile as the Asia-Pacific Economic Cooperation group’s president.

– What will the leaders be discussing?

The global economy, climate change, trade, development and health will be among the issues on the agenda.

Theresa May is expected to call for action to prevent terrorist groups using the internet to spread propaganda and information, and she will also push for other countries to do more to tackle climate change.

Although it is not on the agenda, the leaders will also be concerned about the mounting tension over Iran’s activities in the Gulf and the fragile nature of the deal aimed at preventing Tehran developing nuclear weapons.

Ahead of the summit, Mrs May said: “My message to G20 leaders this week is this: it is only through international cooperation and compromise that we can protect our citizens’ security and prosperity and make the world a safer and a better place to live.”

– What else will happen?

Away from the full plenary sessions, leaders will host a series of one-to-one meetings in the margins of the summit.

G20 summit 2016
Theresa May and Vladimir Putin at the G20 in 2016 – they will meet again this year (Stefan Rousseau/PA)

Theresa May will hold talks with Russian leader Vladimir Putin on Friday in their first major meeting since relations were severely strained following the Salisbury nerve agent attack.

Elsewhere, US President Donald Trump is expected to meet China’s Xi Jinping on Saturday with the eyes of the world on whether their talks can avoid a full-scale trade war which could have major implications for the global economy.