Just a year ago, Greta Thunberg was a relatively unknown teenage girl living in Sweden. Fast-forward and Thunberg’s face has appeared on the cover of renowned magazines and has been photographed alongside the most famous politicians in the world.

So, who is she? Well, to start, Margaret Atwood has called the 16-year-old environmental activist “the Joan Arc of climate change.” And with good reason: At age 15, Thunberg began skipping school every Friday to demonstrate outside of the Swedish parliament, urging her government to meet their zealous goals to curb carbon emissions.

And her unyielding dedication is starting to pay off. In September 2019, millions of people banded together to support Thunberg’s mission to save the planet. Here are five things you should know about Greta Thunberg, the leading face of action against climate change.

1. She is TIME’s person of the year for 2019

On Wednesday, TIME magazine named Greta Thunberg as its Person of the Year, underlining her prominent efforts to prevent irreversible climate change.

In her feature, Charlotte Alter, Suyin Haynes, and Justin Worland wrote:

“Thunberg is not a leader of any political party or advocacy group. She is neither the first to sound the alarm about the climate crisis nor the most qualified to fix it. She is not a scientist or a politician. She has no access to traditional levers of influence: she’s not a billionaire or a princess, a pop star or even an adult. She is an ordinary teenage girl who, in summoning the courage to speak truth to power, became the icon of a generation. By clarifying an abstract danger with piercing outrage, Thunberg became the most compelling voice on the most important issue facing the planet.”

2. By the age of 16, she had addressed two United Nations summits

Last year, Thunberg spoke at the United Nations COP24 Climate Summit in Poland. According to CNN, the combination of climate talks at this summit resulted in nearly 200 nations coming to a compromise on rules that will govern the Paris Climate Agreement.

This year, Thunberg traveled to the U.S. to speak to hundreds of world leaders at the New York United Nations. Her tearful, impassioned speech urging leaders to wake up to the reality of “the beginning of the mass extinction” went viral.

3. She led the largest climate rally ever

Thunberg is a shining example that age is but a number. She led potentially the largest climate rally ever during September’s Global Climate Strike where crowd sizes were estimated to be between 4 million to 7.6 million people.

This rapidly became a global event, as millions marched through cities around the world. On Sept. 20, and during the weeks following, millions marched through cities around the globe. “This is an emergency,” she told the masses. “Our house is on fire.”

4. She’s testified before Congress

When I was 16, I was deciding what dress to wear to prom. Thunberg, however, was testifying before Congress.

In September, the activist went to Washington to discuss the global climate. Quite characteristically, she didn’t take a typical approach to her opening statement. Rather, Thunberg simply offered a copy of the 2018 global warming report by the Intergovernmental Panel on Climate Change, which details the threat of climate and economic impacts along with human-caused global warming.

Her main message? “Do something.”

5. She is on the Autism spectrum

Greta Thunberg is on the Autism spectrum. She has Asperger’s, which is a neurological disorder characterized by difficulty with social and communication skills.

Thunberg has inspired many others with the disability by treating it as anything but a hindrance. In a tweet, the activist wrote that “being different is her superpower.”

“I see the world a bit different, from another perspective,” Thunberg told the New Yorker. “I have a special interest. It’s very common that people on the autism spectrum have a special interest.”