This year will be one of the busiest for elections in recent memory, with half of the world's population living in countries that will go to the polls.

Around 30 countries will elect a president, and another 20 their parliament.

Observers warn of a risk in places of disinformation and manipulation of the process through use of artificial intelligence.

Here is a recap of some of the most hotly anticipated contests:

Trump-Biden rematch?

On 5 November, Americans will choose their next president in a race that could see bombastic ex-president Donald Trump win back the White House despite facing 91 felony counts.

Polls have shown that a majority of voters think that Joe Biden, the gaffe-prone Democratic incumbent, is too old to be commander-in-chief but he remains virtually unchallenged within his party for the Democratic nomination.

Disinformation looks set to be a feature of the campaign, a hangover from the last foul-tempered contest that ended with Trump supporters storming the US Capitol to try to halt the certification of Biden's victory. 

Trump has emerged as the runaway front-runner among Republican candidates since the beginning of its nomination contest, recently scoring a landslide win in Iowa.

Six more years of Putin?

Russian President Vladimir Putin, riding high on his claim to have the upper hand in the Ukraine war two years after Moscow's invasion, is hoping to extend his 24-year rule by another six years in March elections.

Putin is running for a fifth term, which would keep him in power until 2030.

In 2020, he had the constitution amended to allow him to theoretically stay in power until 2036, which could potentially see him rule for longer than Joseph Stalin.

With the war in Ukraine being used to lock up or silence dissenters and opponents, there is little standing in his way.

His long-time nemesis, opposition leader Alexei Navalny, is serving a 19-year prison sentence.

Modi mania

Nearly one billion Indians will be called on to vote in April-May when the world's most populous nation goes to the polls in an election in which Prime Minister Narendra Modi and his nationalist BJP party are seeking a third term.

Modi's political career and success have been based on support from India's one-billion-plus Hindus and, critics say, stoking enmity toward the country's large Muslim minority.

Despite a crackdown on civil liberties on his watch, he goes into the vote the clear favourite, with his supporters crediting him with boosting his country's standing on the global stage.

Battle for Europe

The world's largest transnational election in June will see more than 400 million people eligible to vote in the European Parliament election.

The vote will be a test of support for right-wing populists, who have the wind in their sails after the victory of Geert Wilders's anti-Islam, anti-EU PVV Freedom Party in November's Dutch elections, and last year's win for Giorgia Meloni's far-right Brothers of Italy.

Brussels can take heart however from Poland, where former European Council president Donald Tusk has returned to power on a solidly pro-EU platform.

Mexico's first woman president?

A leftist former mayor of the capital and a businesswoman with Indigenous roots are both vying to make history in Mexico in June by becoming the first woman president of a country with a tradition of machismo.

The election is seen as a two-horse race between former Mexico City mayor Claudia Sheinbaum, who is running on behalf of outgoing President Andres Manuel Lopez Obrador's Morena party, and Xochitl Galvez, representing an opposition coalition, the Broad Front for Mexico.