What does 'Black Lives Matter' mean?

To be honest, I don't think I'd ever heard about 'Black Lives Matter' until George Floyd was killed in Minneapolis and a white police officer named Derek Chauvin was arrested after numerous videos showed the officer kneeling on Floyd's neck while Floyd screamed he could not breathe.

But I did learn that the Black Lives Matter movement first began in 2013 after George Zimmerman shot an unarmed 17-year old black teenager named Travon Martin in February, 2012.

But I do wonder what Black Lives Matter really means. Is it that black lives only matter if they are killed by a white person or a white p...