On Sunday night at the 75th Golden Globes, Hollywood A-listers donned black-and-white TIME'S UP pins, wore black as a show of solidarity and listened as Oprah Winfrey gave a rousing speech declaring the "time is up" for powerful men who are not held accountable for their actions.

» RELATED: Oprah's powerful Golden Globes speech (transcript, video)

On Twitter, the hashtag #TIMESUP spread like wildfire.

» RELATED: From Weinstein to Lauer: A timeline of 2017's sexual harassment scandals

But what is the TIME'S UP movement, exactly?

Flyer from the TIME’S UP GoFundMe page.

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The leaderless, volunteer-led initiative "addresses the systemic inequality and injustice in the workplace that have kept underrepresented groups from reaching their full potential," according to the official TIMES'S UP website, timesupnow.com.

The site describes the movement as “a unified call for change from women in entertainment for women everywhere. From movie sets to farm fields to boardrooms alike, we envision nationwide leadership that reflects the world in which we live.”

» RELATED: Golden Globes center on politics, social issues this year

How did it start?

On New Year's Day, more than 300 leading women in Hollywood published a letter unveiling the movement in the New York Times. The "anti-harassment action plan" was formed soon after the Harvey Weinstein news and is a direct response to the #MeToo movement that sparked a national conversation around sexual harassment and assault and the ousting of prominent men accused of such acts across multiple industries.

» RELATED: #MeToo: Women share harrowing accounts of sexual assault, harassment

Producer Shonda Rhimes, director Ava DuVernay and actress Reese Witherspoon are among the high-profile organizers.

What does the initiative do?

1. Manages a legal defense fund aimed at helping underprivileged women fight against sexual harassment and assault — and retaliation.

In November, 700,000 female farmworkers signed a letter of solidarity, saying they stand with Hollywood actors against sexual assault. Now, TIME'S UP invites everyone to sign their own letter of solidarity with women across all industries.

"It's very hard for us to speak righteously about the rest of anything if we haven't cleaned our own house," producer Shonda Rhimes, a prominent member of TIME'S UP, told the New York Times.

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“If this group of women can’t fight for a model for other women who don’t have as much power and privilege, then who can?” she said.

As of Monday morning, the fund has raised more than $16 million with help from more than 14,000 people in 18 days.

More about the fund, from the GoFundMe page:

“TIME’S UP Legal Defense Fund will provide subsidized legal support to women and men who have experienced sexual harassment, assault, or abuse in the workplace and while in pursuit of their careers. The Fund will ultimately be housed at and administrated by the National Women’s Law Center, an established, national women’s rights legal organization. A network of lawyers and public relations professionals across the country will work with the Center’s Legal Network for Gender Equity to provide assistance to those ready to stand up. Access to prompt and comprehensive legal and communications help will mean empowerment for these individuals and long term growth for our culture and communities as a whole.”

You can donate to the TIME'S UP Legal Defense Fund at gofundme.org.

2. Advocates for women to speak out against sexual harassment

In a moment of solidarity for victims of sexual assault and harassment Sunday, women in Hollywood donned all-black apparel to the Golden Globes.

» RELATED: List of winners for 75th annual Golden Globe Awards

3. Advocates for gender parity

The group advocates for a “significant increase” of women in leadership across all industries, which they say would foster a healthier work environment.

In a letter announcing the movement to the New York Times on New Year’s Day, the women wrote, “Unfortunately, too many centers of power — from legislatures to boardrooms to executive suites and management to academia — lack gender parity and women do not have equal decision-making authority. This systemic gender-inequality and imbalance of power fosters an environment that is ripe for abuse and harassment against women.”

» RELATED: Sexual harassment in the workplace: What is it, how to report it and more you should know

4. Creates legislation to target how sexual misconduct is treated

According to the New York Times, TIME’S UP is working on creating legislation to better penalize sexual misconduct. The organization is focusing on the use of nondisclosure agreements, which are often used to keep victims silent, the group said.

Who's in it?

TIME'S UP includes hundreds of Hollywood A-listers and prominent businesswomen, including the aforementioned Shonda Rhimes, Ava DuVernay and Reese Witherspoon. Other members include Ashley Judd, Eva Longoria, America Ferrera, Natalie Portman, Rashida Jones, Emma Stone and Kerry Washington.

Lawyers Nina L. Shaw and Tina Tchen, who served as Michelle Obama’s chief of staff, and Maria Eitel, co-chairwoman of the Nike Foundation, are also members.

Learn more about TIME'S UP at timesupnow.com.