ABC News takes a look back at the Black Lives Matter movement. The phrase "Black Lives Matter" was born in a Facebook post by Alicia Garza in response to the July 2013 acquittal of George Zimmerman, who fatally shot Martin. The movement emerged as a reaction to the perceived violence and systemic racism by police toward African-American communities. <br><br>A man argues with a police officer over the acquittal of George Zimmerman, in New York, July 14, 2013.
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Florida neighborhood watchman George Zimmerman was acquitted of murder in the shooting of Trayvon Martin on July 13, 2013, sparking fury across the country. His acquittal is credited with beginning the Black Lives Matter movement, which first started as a hashtag on social media. To show solidarity, activists began wearing hooded sweatshirts as Trayvon Martin had been wearing the night he died. </br></br>Sam Hill, 11, wipes away tears during a youth service at the St. Paul Missionary Baptist Church in Sanford, Florida, July 14, 2013. Many in the congregation wore shirts with a photo of Martin.
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On July 17, 2014, Eric Garner, 43, died on Staten Island, New York, after he was stopped by several officers who put him in what has been described as a chokehold. His last words, “I can’t breathe,” became a slogan for Black Lives Matter and other protesters. <br> <br>Logan Browning stands with duct tape over her mouth with other demonstrators during a protest against police violence in Hollywood, California, Dec. 6, 2014.
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A year later, on Aug. 9, 2014, Michael Brown, an 18-year-old black man, was fatally shot by Darren Wilson, a white police officer, in Ferguson, Missouri. Protests in the St. Louis area went on for weeks following the shooting, and the Black Lives Matter movement helped organize demonstrations across the country. Wilson was not indicted, and that announcement set off another wave of protests in November of that year. <br><br>Tear gas surrounds a woman kneeling in the street with her hands in the air after a protest for Michael Brown, Aug. 17, 2014, in Ferguson, Missouri.
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Patrisse Cullors, one of the cofounders of the Black Lives Matter movement, emphasized the importance of photography being used by activists on social media to represent the movement. "These images have shaped the ideas about our movement. We have seen black folks resist tear gas, rubber bullets, and racist elected officials. The images have provided hope and strength," she told ABC News. <br><br>A demonstrator throws a tear gas container during a protest over the shooting death of Michael Brown, Aug. 13, 2014, in St. Louis, Missouri.
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Patrisse Cullors said that through images of the movement she sees "the urgency in Black America, the fight, resilience, rage and desperation." </br></br>Police fire tear gas during a protest over the death of Michael Brown in Ferguson, Missouri, Aug. 18, 2014.
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Protesters march in the street as lightning flashes in the distance in Ferguson, Missouri, Aug. 20, 2014.
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A man is doused with milk and sprayed with mist after being hit by an eye irritant from police in Ferguson, Missouri, Aug. 20, 2014, during the protests over the death of Michael Brown.
Michael Brown Sr. cries out as his son's casket is lowered into the ground at St. Peter's Cemetery in St. Louis, Missouri, Aug. 25, 2014.
Pastor Charles Burton lies on the driveway at the Ferguson, Missouri, police station as a chalk drawing is made as a memorial to Michael Brown, Oct. 13, 2014.
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Months after Michael Brown’s death, Laquan McDonald, 17, was shot 16 times and killed on Oct. 20, 2014, in Chicago. Protests broke out after police dashcam footage was released showing the fatal exchange between the police officer and McDonald, appearing to contradict officers’ accounts. </br></br>Demonstrators hold a "Laquan" sign, Nov. 24, 2015, in Chicago following the release of police dashcam video of the shooting death of Laquan McDonald by Chicago police officer Jason Van Dyke. He was charged with first-degree murder and has pleaded not guilty. As of Jan. 29, he is awaiting trial.
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On Nov. 25., 2014, a grand jury decided there was not enough probable cause to indict police Officer Darren Wilson in the shooting death of Michael Brown, leading to more protests across the U.S. In this photo, police Sgt. Bret Barnum hugs 12-year-old Devonte Hart during a demonstration calling for police reform in Portland, Oregon.
Bishop Derrick Robinson, who had become a notable leader among the Ferguson protesters, was arrested by riot police while protesting in a public park after a non-violent march outside a football game, Nov. 30, 2014, in St. Louis.
Just before the controversial grand jury decision in the Michael Brown shooting case, 12-year-old Tamir Rice was shot to death in Cleveland on Nov. 22, 2014. Tamir was playing with a toy gun in a public park when officers mistook it for a real gun, and Officer Timothy Loehmann shot him at point-blank range seconds after arriving on the scene. <br><br>In December 2015, protesters took to the streets of downtown Cleveland the day after the local grand jury decided not to indict Loehmann and his partner.
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People join in the National March Against Police Violence, which was organized by the National Action Network, Dec. 13, 2014, in New York. The march coincided with a march in Washington, D.C., following two grand jury decisions not to indict white police officers in the deaths of unarmed African-American men by police.
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Protesters congregate at the Alameda County Court House during a “Millions March” demonstration protesting the killing of unarmed African-American men by police, Dec. 13, 2014, in Oakland, California. The march was one of many held nationwide.
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People join hands during the National March Against Police Violence, which proceeded down Broadway to the headquarters of the New York Police Department Dec. 13, 2014, in New York.
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Demonstrators stage a die-in at the Chicago Water Tower in Chicago during a march along the Magnificent Mile shopping district on Michigan Avenue to protest police abuse, Dec. 13, 2014.
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Photographer Sheila Pree Bright said, “From this particular protest it showed me how young people from all backgrounds came together in solidarity with the Black Lives Matter movement. I truly believe the young people are the ones who will bring about true change.” <br><br> Children carry signs during a demonstration organized for Michael Brown calling for national solidarity in Ferguson, Missouri, March 20, 2015.
Sheila Pree Bright
Black Lives Matter protesters took to the streets again following the fatal shooting of Walter Scott, whose coffin is seen above. Scott, 50, was pulled over for a broken tail light, April 4, 2015, in North Charleston, South Carolina, and subsequently shot and killed by Officer Michael Slager. Cellphone video recorded by a passerby appears to show Scott being shot in the back as he is running away, seemingly contradicting the officer’s testimony and sparking outrage nationwide. Slager’s first state criminal trial ended in a hung jury. His federal civil rights trial is scheduled for this spring.
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Two weeks after Walter Scott’s shooting, Freddie Gray, 25, died, April 19, 2015, after his arrest a week earlier by Baltimore police. An autopsy concluded that his death was caused by a "high-energy" injury to his neck and spine that likely occurred while Gray was in the back of the police van. <br><br>Hundreds of demonstrators march toward the Baltimore Police Western District station during a protest against police brutality and the death of Gray in the Sandtown neighborhood April 22, 2015, in Baltimore.
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Though the medical examiner ruled Freddie Gray’s death a homicide, none of the six officers charged were found guilty. Each officer was given a separate trial. One ended in a mistrial, three resulted in aquittals and then all remaining charges were dropped. </br></br>People wait for the bus while police secure Mondawmin Mall, April 29, 2015, in Baltimore, where riots broke out on the day of Freddie Gray’s funeral. A state of emergency was issued and National Guard troops were deployed following the violent gathering where people threw objects at police, set cars on fire and looted businesses.
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Photographer Devin Allen's photo from the Freddie Gray protests in Baltimore on April 25, 2015 made the cover of Time magazine's May 11, 2015, issue with the year "1960" crossed out and replaced with "2015" with the text "What Has Changed and What Hasn't." Allen first published the image on his Instagram and Twitter accounts after being unable to get his images from other protests published. "I used Instagram, Twitter to get my photos out. Social media is a game changer for journalism. It gives people that can’t be heard a voice," he said.
A boy looks out a bus window at a line of National Guard and police officers in riot gear in the Winchester-Sandtown neighborhood of West Baltimore, May 1, 2015, after charges were announced for six officers in connection with the death of Freddie Gray.
People celebrate after charges were announced against the police officers involved in the death of Freddie Gray in the Winchester-Sandtown neighborhood of West Baltimore, May 2, 2015. Marilyn Mosby, state’s attorney for Baltimore, indicted all six officers involved with criminal charges, stating that Gray's death was a homicide case.
A partially burned American flag lays on the street near the spot where Michael Brown was killed before an event to mark the one-year anniversary of his death in Ferguson, Missouri, Aug. 9, 2015. Hundreds of people marched, prayed and held moments of silence in Ferguson to mark the anniversary.
Mecca Verde, 18, stands with other demonstrators of the Black Lives Matter movement at the Inner Harbor protesting the confirmation of Kevin Davis as the new Baltimore city police commissioner in Baltimore, Oct. 19, 2015. Protesters opposed his confirmation, stating that he did not reach out to residents to learn the issues plaguing their community after the riots in April and the steady rise in homicides.
Philando Castile, 32, was shot multiple times by police Officer Jeronimo Yanez after being pulled over for a broken tail light, July 6, 2016, in Falcon Heights, Minnesota. The gruesome aftermath was streamed live on Facebook by Castile’s girlfriend, Diamond Reynolds, who was sitting next to him in the car when he was killed. On Nov. 16, 2016, Yanez was charged with second-degree manslaughter and two counts of dangerous discharge of a firearm. He is awaiting trial. <br><br>Demonstrators march to protest the shooting death of Philando Castile, July 9, 2016, in St. Paul, Minnesota.
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People protest the police shootings during five days of demonstrations on July 11, 2016, in Atlanta following the deaths of Philando Castile outside St. Paul and Alton Sterling in Baton Rouge. Sterling was shot and killed while pinned to the ground during an altercation with two police officers outside a convenience store on July 5, 2016. Crowds gathered in protest after a graphic video of the incident was posted online. The officers involved in Sterling’s death have yet to have charges brought against them, but as of July 7, 2016, a civil rights investigation was opened by the DOJ.
Sheila Pree Bright
Dallas Police Chief David Brown pauses at a prayer vigil following the deaths of five police officers during a Black Live Matter march, July 8, 2016, in Dallas, Texas. </br></br>Five police officers were killed and seven others were injured in a coordinated ambush at an anti-police brutality demonstration in Dallas following the deaths of Philando Castile and Alton Sterling. The gunman, Micah Xavier Johnson, who was black, had previously expressed anger at police and white people. After a standoff he was killed when police detonated an explosive strapped to a robot.
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A man protesting the shooting death of Alton Sterling is detained by law enforcement near the headquarters of the Baton Rouge Police Department in Baton Rouge, Louisiana, July 9, 2016.
Ieshia Evans is detained by law enforcement in Baton Rouge, Louisiana, July 9, 2016, during a demonstration following the shooting of Alton Sterling.
Keith Lamont Scott, 43, was killed, Sept. 20, 2016, in Charlotte, North Carolina, by Brentley Vinson, an African-American police officer. Police stated that Scott had a handgun and did not comply with the officer's instructions to "drop the weapon." Kerr Putney, chief of Charlotte-Mecklenburg police, said that a handgun was seized at the scene. <br><br> Police officers wearing riot gear block a road during protests after police fatally shot Keith Lamont Scott, 43, in the parking lot of an apartment complex in Charlotte, North Carolina, Sept. 20, 2016.
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Attorney General Loretta Lynch launched an investigation into Keith Lamont Scott's shooting death with the DOJ and found officer Brentley Vinson "acted lawfully" and no charges were brought against him. </br></br>Police officers face off with protesters during protests in the early hours of Sept. 21, 2016, in Charlotte, North Carolina, following the fatal shooting of Keith Lamont Scott. The shooting sparked a week of sometimes violent demonstrations which caused some businesses to close, the deployment of National Guard troops and the declaration of a state of emergency by Gov. Pat McCrory.
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A woman smears blood on a police riot shield, Sept. 21, 2016, in Charlotte, North Carolina.
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Demonstrators attempt to make their way onto Interstate 277 to block traffic as they march in the streets amid a heavy police and National Guard presence as they protest the death of Keith Lamont Scott, Sept. 22, 2016, in Charlotte, North Carolina.
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