The slogan “Black Power” was was a political montra and name for multiple ideologies directed at achieving self determination for black people.
The slogan was introduced by Stokely Carmichael, otherwise known as Kwame Ture, during his chant at a 1966 march in Mississippi. The black power movement emphasized racial pride. It also pushed the creation of black cultural and political institutions.
You might be asking why the black power movement isn’t merely considered to be a part of the civil rights movement. The difference between the black power movement and the civil rights movement was that the black power movement was not completely nonviolent. The phrase seemed to electrify its audience and motivated an increasing radicalization through the colored movement.
The slogan sturred much emotion and was expressed in many ways. To some it meant black capitalism, others it was black cultural nationalism, and to others it was the black radical tradition. This slogan encouraged the creation of many groups like the Black Panthers, as well as the Revolutionary Union Movements. The ideology helped create much sympathy and compassion towards the black struggle throughout the US. The movement inspired an entire generation through its actions and ideas. The movement also was expressed through a slightly more negative approach.
Radicals expressed their grievances through a more political and military step of action. It encouraged the belief that the government acting according to its stated principles of equality and justice was not enough. The way to transform society must be done through a militant form of struggle.