(CNN)These days, it feels like there's a petition for every cause imaginable.
But some petitions are more successful than others.
The petition-hosting site Change.org considers a number of factors in determining which had the biggest impact: the number of people who signed, the zeitgeist and the conversations sparked and whether anything changed as a result, said Michael Jones, the platform's managing director of campaigns.
"People really see online petitions as a tool to help them fix something that is systemically broken," Jones said.
Over the past decade, people took to Change.org to raise attention to criminal justice issues, honor community heroes and challenge pharmaceutical companies and other businesses.
These are 10 of the biggest victories, according to Change.org.
Justice for Trayvon Martin
After 17-year-old Trayvon Martin was was killed on February 26, 2012, his parents Tracy Martin and Sybrina Fulton started a petition calling for the arrest of George Zimmerman, the neighborhood watch leader who shot him.
More than 2.2 million people signed in support of the cause. Within a week, it had become the one of the most popular petitions in the website's history, with 877,110 signatures.
The local tragedy soon became an international movement. Civil rights activists, politicians and protesters rallied behind Trayvon's family and took to the streets to demonstrate against his killing.
In April 2012, Change.org declared the petition a victory after a Florida state attorney announced that charges of second-degree murder would be lodged against Zimmerman.
Zimmerman was acquitted in 2013. But Trayvon's death forced a conversation about police brutality and inequality and helped give rise to one of the most prominent movements of the decade: Black Lives Matter.
Zimmerman is now suing Trayvon's parents, prosecutors and state authorities, alleging there was a conspiracy to frame him and demanding more than $100 million in damages.
Trayvon's parents and their attorney called the lawsuit "unfounded and reckless."
Preventing animal cruelty
Maryland high school student Sydney Helfand started a petition in January urging Congress to pass the Preventing Animal Cruelty and Torture (PACT) Act to make animal cruelty a federal felony.
The PACT Act had come extremely close to becoming law in 2017. Though the Senate passed it unanimously, it stalled in the House.
Nearly 800,000 people signed the petition and in November, the Senate passed the bipartisan legislation that the House had approved a month earlier.
US Rep. Ted Deutch of Florida credited Helfand, in part, for the bill's success. President Donald Trump signed the PACT Act into law.
Passing Caylee's Law
As the trial of Casey Anthony, who was accused of killing her 2-year-old daughter Caylee in 2008, played out in 2011, a petition called for the creation of Caylee's Law, which would make it a felony for a parent of a guardian to fail to report a missing child if the child could be in danger.
It was one of the first petitions of the decade to go viral, Change.org says, ultimately attracting more than 1.3 million signatures.
At least 10 states since then have passed versions of Caylee's Law. Critics say the laws would negatively affect mostly innocent parents who may be grieving the tragic loss of a child.
Saving Rodney Reed
Death row prisoner Rodney Reed was sentenced more than 20 years ago for the 1996 murder of 19-year-old Stacey Stites in Bastrop, Texas.