The #BlackLivesMatter movement is a movement specifically targeting police brutality against black people. It was founded because police were and are shooting unarmed black people and not being held accountable for their deaths. If you talk to anyone who has been involved with the #BlackLivesMatter movement, they will tell you that there is NOT an invisible 'only' in front of the hashtag. They're more likely to say there's actually an invisible 'too' at the end. BlackLivesMatter doesn't mean only black lives matter, nor is it a proclamation that black lives matter more. BlackLivesMatter is a declaration that black lives matter just as much as other lives, and police who unjustly end those lives should be held accountable.
When explaining the BlackLivesMatter movement to people who may not understand or see the necessity of the movement, analogies are often used. For example, imagine that your house is on fire. When the fire department arrives and you tell them that your house is on fire, you don't expect them to say "All houses matter!" and spray water on each house on the block. While it is true that all houses matter, the focus should be on the house that is currently on fire and in danger of being destroyed. Black victims of police brutality are the burning house. Statistically, black people are more likely to be killed by police than any other population. Across America, on average, unarmed black people are 3.49 times more likely to be shot by police than unarmed white people. In other words, black lives are more in danger, like the burning house.
Some people will look at that analogy and say that it doesn't make sense because black lives are not the only lives being taken by police. Here is another analogy that may make more sense. Imagine that you have frequent fractures in both your left and right arms. If your left arm breaks 3.49 times as often as your right, it would make sense that you complain to your doctor about your left more than your right. Both arms are important, of course, but the left is harder to protect and needs more support. Similarly, since police kill black people more often than any other race, it makes sense to complain about police brutality against black people more. All lives matter, of course, but black people are harder to protect from police brutality and need more support.
At the end of the day, BlackLivesMatter is outraged by the fact that police who kill black people (both armed and unarmed) do not receive appropriate consequences for their behavior. Many are not even indicted, let alone convicted. At the heart of the movement is the firm belief that cops who kill people and people who kill cops should face the same justice system. If you believe AllLivesMatter, then you believe all criminals should face the same justice system. Sadly, police officers that murder black people do not face the same system as blacks who kill blacks, blacks who kill whites, or black who kill cops. That discrepancy is what BlackLivesMatter is all about.
Some people argue that the BlackLivesMatter movement is anti-police. In fact, the BlueLivesMatter hashtag was created to "defend" police against the BlackLivesMatter movement; however, the two are not mutually exclusive. Again, if you talk to anyone involved in the BlackLivesMatter movement, they will tell you that they are not anti-police. BlackLivesMatter is against police brutality. It is possible to be against police brutality and still care about the lives of innocent police officers. What is more alarming is that so many people feel like you either have to be pro-black or pro-police. Being pro-black lives doesn't automatically make you anti- police lives, and vice versa. That's like saying blacks and police are somehow on opposite sides. Isn't that a scary thought?