Black, chosen for its association with mourning and sorrow, is the color — or anti-color — of choice for the hundreds of thousands of protesters who have taken to the streets in Hong Kong to fight for more democracy in their metropolis. Counter-protesters aligning with the city's pro-Beijing mayor chose white to distinguish themselves.

Hong Kong's protests have not always been in black and white. Back in 2014 during the so-called Umbrella Revolution, when protesters demanded fully free elections and other democratic reforms for their semi-autonomous city, yellow umbrellas were the symbolic item of choice. Protesters used them to fend off tear gas released by police.

Replacing the color red, which many associate with communism in the Soviet Union, orange was the color of choice for the opposition during Ukraine's "Orange Revolution" in 2004. For 17 days in the harsh Ukrainian winter, members of different social classes came together on behalf of opposition candidate Viktor Yushenko.

The peaceful 2007 demonstrations in Myanmar became known by the color saffron — the typical hue of Buddhist monks' robes. At the forefront of the protests against the military government, the monks were joined by students and political activists, including many women.

After three years of demonstrations from 1983 to 1986 against president Ferdinand Marcos and his regime, citizens of the Philippines triumphed in a peaceful revolution. It's commonly referred to as the "Yellow Revolution" for the color of the ribbons protesters held during their gatherings. The image above shows yellow confetti thrown in honor of the revolution's anniversary in 2013.

Green is considered the color of Islam and was chosen by protesters fighting the government during the 2009-2010 elections in Iran: Demonstrators accused the regime of falsifying election results. The regime reacted swiftly, injuring defenseless protesters and arresting around 4000 people. Today, the demonstrations are still referred to as the "Green Movement."

Why choose one color when you can have them all? To protest against the government's decision to call off an investigation into a wiretapping scandal in 2016, Macedonian protesters gathered in the nation's capital in mid-April to show their discontent. Many threw colored paint at government buildings, achieving an effect similar to that of artist Jackson Pollock's famous splatter masterpieces.

Not only colors but also flowers have come to symbolize significant protests in modern history. After a successful coup in Portugal on April 25, 1974 that ended years of dictatorship, overjoyed citizens celebrated by putting red carnations in the guns of their victorious fighters. It was the blossoming of a new era of democracy in Portugal, followed by similar developments in Spain and Greece.

In Moldova, the "Grape Revolution" was the name given to protests of the parliamentary election results in 2009: After the Communist party was successful, demonstrators took to the streets. The name reportedly referenced the country's numerous vineyards. The revolution did not grow to the magnitude of those in other countries once belonging to the Soviet Union, such as Ukraine.

For 28 days in 2011, Tunisians stormed the streets to protest corruption, unemployment and poor living conditions. Interestingly, the name "Jasmine Revolution" was popular with Western media, but not with Tunisians. Instead, Tunisian's referred to it as the "Dignity Revolution," since the ousting of the previous President Ben Ali in 1987 was also called the "Jasmine Revolution."