- How many countries? -

A total of 189 countries plus the EU have delegations at the conference, the UN Climate Change agency told AFP on Monday.

But for the first time in COP history, the United States is a no-show because climate-skeptic President Donald Trump decided to shun the event.

Afghanistan was not invited and the Taliban government has voiced disappointment over being excluded.

COP30 is the 30th meeting of the 198 parties to the 1992 United Nations Framework Convention on Climate Change.

It also serves as the meeting of the 195 parties to the 2015 Paris Agreement (194 countries, plus the EU) -- and is the forum for the most important climate-related negotiations.

All decisions must be made by consensus, which theoretically allows any one of the parties to block an agreement.

- How many people are participating? -

About 44,000 people have been accredited to attend COP30 in person, according to UN Climate Change.

This includes national delegations, their guests, businesses, observers, and members of the media. The figure excludes approximately 6,000 virtual accreditations.

As of Saturday, 26,500 of them had arrived in person, the UN told AFP, including more than 2,100 journalists.

The number is expected to continue to rise during the last five days of the conference.

According to final attendance figures, the media outlet Carbon Brief estimates that COP30 could be the fourth largest COP ever held, the largest being Dubai in 2023.

- How long does it last? -

COPs are held every year in November and last two weeks, usually ending on a Friday.

But no COP has concluded on time since 2003, with negotiators often spending an extra sleepless night to reach agreements. Sometimes it can take two extra nights, as was the case at COP27 in Egypt in 2022.

COP30 kicked off on November 10 and is scheduled to end on November 21.