Black Lives Matter was born in 2012 after the shooting death of Trayvon Martin in Florida.
What began as a simple hashtag on social media has since grown into a fully-fledged movement within the African-American community.
Martin's killer, neighborhood watch volunteer George Zimmerman, was cleared of any wrongdoing, giving rise to protests nationwide.
Today, the movement has taken center stage as followers demonstrate against the shooting of black Americans at the hands of police.
Some critics say the group incites violence against police officers, and chooses their outrage selectively, staying silent about black on black crime.
The group's founders insist Black Lives Matter is not encouraging violence.
"The reality is this is a peaceful, human rights movement led by incredible courageous black people," says co-founder Opa Tometi. "I think we are demanding justice, and freedom for our people."
Randi Kaye, a founder of the movement, says she hopes that Black Lives Matter shines a light on racial injustice.
The dozens of chapters of BLM across the country have been a visible front in the deaths of not just Trayvon Martin, but Michael Brown in Ferguson, Mo.; 12-year-old Tamir Rice, in Cleveland, Ohio; Tony Robinson, in Madison, Wis.; Eric Harris, in Tulsa, Okla.; and Freddie Gray, in Baltimore, Md.
"They need to take care of our country," says Ashley Sharpton, a Black Lives Matter participant. "If the police are supposed to protect us, then they need to make sure that they insure that."
What does Black Lives Matter hope to accomplish?
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