After a week that saw two new videos of unarmed black men dying at the hands of law enforcement and police themselves being gunned down by a sniper, the Black Lives Matter social justice movement has come under increased scrutiny.

So, to try and simplify things, here’s what Black Lives Matter is and what its activists want.

How it Started

Following the 2013 acquittal of George Zimmerman, who killed Trayvon Martin — an unarmed black teenager in Florida — in 2012, activists and organizers Patrisse Cullors, Alicia Garz and Opal Tometi started the Black Lives Matter movement as a hash tag and a political project. At the time, Garza reacted in part by writing a Facebook plea for the violence against black people to stop. He ended his appeal with the three words, “black lives matter.” The post resonated across the nation and the movement ultimately gained widespread media attention after two more unarmed black men — Eric Garner and Michael Brown — were killed by police in 2014.

How is the Movement Organized?

Black Lives Matter is partly difficult to define because it has a decentralized structure and, therefore, a variety of specific goals depending on specific locations. The overall organization is a network of local chapters with individual leadership structures across the country. The idea behind that approach is to affect change from the grassroots on up instead of trying to tackle the problem at the much bigger, and much more difficult, national level.

What Do They Want?

The movement, at its most obvious level, wants the disproportionate level of state violence against black people to stop. Beyond that, the movement also says it wants all systematic and intentional targeting against all people to stop. The Black Lives Matter website says organizers and activists are working to support black people, disabled people, the LGBT community and women, as well.