The race for the White House this year is generally described as a competition between Republican Donald Trump and Democrat Hillary Clinton. But in fact, dozens of others are also running.

Since 1869, the occupant of the Oval Office has been either a Democrat or a Republican. But with this year’s main contenders being unprecedentedly unpopular, other candidates have gained some traction.

Because of the way the American political system is built, so-called third-party candidates basically have zero chances of winning..

WATCH: Does voting third party mean a Donald Trump victory?

Under the electoral college vote, the popular vote does not matter. Instead, within each state, the candidate who wins the most votes takes all that state’s electoral votes.

The term third-party is used for American political parties other than the Republican and Democratic parties.

These are some of the more prominent, or colourful, candidates.

[Reuters]

Gary Johnson - Libertarians

Formerly a Republican. Was governor of New Mexico from 1995 to 2003. Made headlines in September when he said "What is Aleppo?" in response to a question about the war in Syria.

The party believes in a reduced role of the government. Several of its members hold elected office in state and local government.

Johnson got 1,275,971 votes (0.99 percent of the popular vote) in 2012.

[Reuters]

Jill Stein - Green Party

A physician, politician and activist. Was the member of the Lexington, Massachusetts local government from 2005 to 2011.

The party describes itself as "eco-Socialist" and anti-war, propagating environmentalism and social justice.

Stein won 469,501 votes (0.36 percent of the popular vote) in 2012.

[Reuters]

Evan McMullin - Independent

The former CIA officer markets himself as a conservative alternative to Trump and Clinton.

Has come up as a potential challenger to the Republican in his home state, Utah.

When Trump said he had never heard of him, McMullin hit back, saying:  "You've never heard of me because while you were harassing women at beauty pageants, I was fighting terrorists abroad."

[Al Jazeera]

Darrell Castle - Constitution Party

A lawyer who served as a Marine during the Vietnam War.

Formerly the American Taxpayers Party, the party advocates a strict interpretation of the Constitution and more power for states and localities.

 

Jim Hedges - Prohibition Party

Born in Iowa, Hedges served as a musician in the US Marines, later becoming a community organiser, and a volunteer with the Salvation Army.

Campaigning on a socially conservative Prohibitionist Party platform, Hedges believes in highlighting the dangers of drinking alcohol, drug taking, gambling, and spousal abuse, among other things.

Laurence Kotlikoff - It's Our Children

The Harvard-educated economist at Boston University has made the economy the focus of his campaign.

Kotlikoff wants to tackle the fall in real wages and warns that low-skilled legal immigration is pricing out American workers from the jobs market.