The world changed in the wake of the terrorist attacks of 9/11 in 2001 and for historians, the attacks marked the turn of the century. But since then and until now, many are the milestones that have transformed the reality of the world. AL DÍA has collected 20 historical events of the past 20 years since the Twin Towers fell.

In January 2002 the Euro became the currency of the European Union. It was adopted by 12 of its 15 member states — among them, Germany, Spain and France. The only major country left out of this change was the U.K., as a premonition of its future exit from the EU.

With the expansion of the institution to 27 countries, today, there are 19 that use it as currency. In total, 340 million citizens spend with euros, making it the second most traded currency in the world after the dollar.

A year and a half after the 9/11 attacks, the United States, the United Kingdom, Australia, and Poland invaded Iraq, marking the start of the Iraq War. According to President George W. Bush, the goal was "to disarm Iraq of weapons of mass destruction," but they were never found, and also to "liberate the Iraqi people" from Saddam Hussein.

The war caused a political fracture between the great powers. France, Germany, Russia and China opposed the invasion while Spain and the United Kingdom supported the United States. Another historical event also accompanied the invasion: the first world demonstrations against a conflict.

On March 11, 2004, Al Qaeda committed the most serious terrorist attack in European history. Four commuter trains exploded on their way to Madrid, leading to 200 deaths. The government, which was facing an election three days later, claimed that the attack had been perpetrated by the terrorist group ETA.

The administration's fear of admitting that the attack had been produced by his support for the invasion of Iraq led him to try to hide the real perpetrators in Al Qaeda. But the news landed first and the government lost the election to the Socialist Party.

Pope John Paul II began his papacy in 1978 and died in 2005. It was necessary to wait for Francis' pontification for his canonization, which arrived in 2014.

He became the first Polish pope in history and the first non-Italian since the 16th century. After his death, the conclave elected Ratzinger pope, who chose the name, Benedict XVI.

It was a year of elections that confirmed the triumph of the left on the continent.

Evo Morales won the Bolivian elections. He was the first indigenous president, as well as a prominent trade unionist. It was also the year that Venezuela re-elected Hugo Chávez, who won the elections for the first time in 1998, after the failed 1992 coup. His re-election came after winning the presidential referendum in 2004.

Lula da Silva was also re-elected by the Brazilians that year. A metalworker and trade unionist, he won his first election in 2003. It would take another year for Rafael Correa to win the presidency in Ecuador, consolidating the left in Latin America.

Some smartphones already existed, but Apple's iPhone revolutionized the world. The first mobile phone with a camera, music player and software to send and receive text messages, all in one device.

Steve Jobs announced its arrival and that year, Time magazine named it Invention of the Year.

On Sept. 15, 2008, Lehman Brothers filed for bankruptcy. The investment bank had taken too many risks in the subprime mortgage market.

Its bankruptcy, the largest in the history of the United States, was the beginning of the global financial crisis that devastated the economy of half the world.

Barack Obama became the first Black president of the United States.

In his first speech to the nation, he promised to close the Guantánamo Bay prison as soon as possible, a promise that he failed to fulfil in both of his two terms. What he did achieve was to establish Obamacare and extend basic health care to millions of Americans.

Two earthquakes shake Chile and Haiti.

In the Chilean sea is where a February earthquake had its epicenter, which lasted four minutes on the coast and two in its capital of Santiago. It led to 525 deaths.

In Haiti, the earthquake had its epicenter 15 kilometers from the capital, Port-au-Prince. It was the strongest in the area since 1770 and one of the most devastating in human history. The dead were more than 316,000.

After a magnitude nine earthquake in Japan created a tsunami off the northeast coast that hit the Fukushima nuclear plant.

The power supply to the reactors failed and there were three hydrogen explosions that released radioactive contamination. There was no nuclear explosion and luckily, the accident resulted in only one death. As for the earthquake, that's a different story.

The first major social network went public, reaching a valuation of $104 billion on its first day. It broke the record as the company with the highest value at the beginning of its listing. It now has more than 2.7 billion users worldwide.

In 2013, Pope Benedict XVI announced his desire to resign from the papacy and the conclave elected the first Latin American pope, Francis.

For the first time, two popes lived together because the position is for life. Pope Francis is known for his humility and closeness to the poor, in addition to his commitment to dialogue with other religions.

Government technology consultant Edward Snowden disclosed classified NSA documents and secured his residence in Russia.

A year earlier, the agency's mass surveillance programs had been published due to Snowden's leaks through The Guardian and The Washington Post, causing a great international commotion. In addition, it was a major diplomatic crisis between the United States and many of its allies, who were known to have been spied on.

On Jan. 7, 2015, two masked men armed with assault rifles entered the offices of the French satirical magazine Charlie Hebdo. The religious fanatics fired 50 shots, killing 12 workers and wounding 11 others. In their flight, they also killed a police officer.

The publication had published cartoons physically depicting the Prophet Muhammad, a taboo in Islam.

Al Qaeda claimed responsibility for the attack and two days later, French soldiers killed the two terrorists. On Jan. 11, 2 million people, including more than 40 heads of state and government from around the world, demonstrated in Paris in support of freedom of expression.

Donald Trump won the U.S. election over Hillary Clinton. That year, he was the 324th richest person in the world, according to Forbes magazine and was the richest president to ever take office.

During his campaign, the use of fake news became popular, which his team defined as “alternative truths.”

On Oct. 1, 2017, the Catalan government decided to hold an independence referendum despite  Spanish courts declaring it illegal.

The state sent thousands of police officers who violently repressed voters in polling stations. The images went around the world.

Although it could not be held under normal conditions, the Catalan government recognized the results and symbolically declared independence three weeks later. Two days later, part of the executive fled into exile in Belgium.

In the 2016 referendum, the Great Britain chose, by very little difference, to leave the European Union.

Two years later, the 27 Member States approved the Exit Agreement and the Declaration on future relations between the EU and the U.K. after Brexit. The final departure did not occur until 2020, after almost 50 years of a relationship.

Social protests around the world had a common component: gender equality.

In 2019, Las Tesis viralized their performance, "A rapist in your path," which became the cry of women around the world. The #MeToo movement had pushed to revitalize feminism since 2017, and in 2018, the first feminist general strike was held in Spain.

Although the coronavirus began to affect China in late 2019, it was not until March 2020 that the World Health Organization declared COVID-19 a global pandemic. In that month, more or less strict confinements were put in place in almost all the countries of the world, which brought a halt to the global economy.

Less than a year after the outbreak of the pandemic, various pharmaceutical companies approved vaccines against COVID-19. Vaccination went global in January 2021, although today many countries are still far from reaching percentages that allow talking about herd immunity.