Get all the latest news on coronavirus and more delivered daily to your inbox. Sign up here.
In mid-March, Gates stepped down from the board of Microsoft, as well as the board of Warren Buffett's company Berkshire Hathaway, so he could dedicate more time to his charity the Bill & Melinda Gates Foundation.
Gates and his wife Melinda founded the organization in 2000 after about three years of starting other philanthropic endeavors including the Gates Library Foundation, which was launched in 1997 and the Gates Millennium Scholarship Program, which was established in 1999, according to the foundation's website.
The organization is focused on poverty, global health and education, according to the website, which said they believe those topics "are the biggest barriers that prevent people from making the most of their lives."
Today, the Bill & Melinda Gates Foundation is the largest private charitable foundation in the world, according to Forbes.
Here's what else you need to know about the foundation.
Warren Buffett is a trustee
The Bill & Melinda Gates Foundation has three co-chairs and three trustees. Gates and Melinda are both co-chairs and trustees, with Gates' father, William Gates, Sr., as the third co-chair and Warren Buffett as the third trustee.
Gates and Buffett have been friends since 1991 when they met at a dinner party, according to Business Insider.
According to a letter from Gates and Melinda on the foundation's website, Buffett once told the couple about philanthropy: "Don't just go for safe projects. Take on the really tough problems."
Since 2006, when he joined the foundation as a trustee, Buffett has donated billions of dollars to the Bill & Melinda Gates Foundation. In 2018 alone, he donated $2.6 billion, according to the website.
It has total assets of more than $51 billion
According to the foundation's audited financial statements from 2019, the organization had total assets of more than $51 billion, up from $47.8 billion in 2018.
The foundation paid out more than $4.6 billion in grants and $423 million in direct charitable support, according to the 2019 statement.
From the beginning of the Bill & Melinda Gates Foundation through 2018, the organization paid $50.1 billion in grant payments, according to the website.
It has promised to donate $300 million to fight the coronavirus
Since January, the Bill & Melinda Gates Foundation has continued to pledge millions of dollars for treatment and prevention of the coronavirus. At first, the organization promised to give $10 million and a month later, it followed up with a pledge of $100 million.
In total so far, the foundation has promised $300 million for the cause, according to Forbes.
It has its skeptics
In 2015, Vox published a report about political scientists and scholars who have concerns about the Bill & Melinda Gates Foundation, particularly a lack of accountability and transparency as a private organization with only three trustees.
There are also some concerns about the foundation’s priorities and focus on health technology as opposed to health systems as a whole.
However, a spokesperson for the organization told Vox at the time: "The question of accountability and transparency is not unique to the Gates Foundation, but is a concern about the role of philanthropy generally."