Black people is a term used in certain countries, often in socially based systems of racial classification or of ethnicity, to describe persons who are perceived to be dark-skinned compared to other given populations. As such, the meaning of the expression varies widely both between and within societies, and depends significantly on context. For many other individuals, communities and countries, "black" is also perceived as a derogatory, outdated, reductive or otherwise unrepresentative label, and as a result is neither used nor defined. 

Different societies apply differing criteria regarding who is classified as "black", and these social constructs have also changed over time. In a number of countries, societal variables affect classification as much as skin color, and the social criteria for "blackness" vary. For example, in North America the term black people is not necessarily an indicator of skin color or majority ethnic ancestry, but it is instead a socially based racial classification related to being African American, with a family history associated with institutionalized slavery. In South Africa and Latin America, for instance, mixed-race people are generally not classified as "black." In South Pacific regions such as Australia and Melanesia, European colonists applied the term "black" or it was used by populations with different histories and ethnic origin.
Is what "black" means consistent across different groups?
Is it used everywhere?
Why not?
What is a basic definition?
In comparison to others?
Where is the term related to slaves?
Does it indicate skin color there?
Where aren't mixed race people described as black?
What is a societal construct for being black?
Where did European colonists use the word black?
No
Black people is a term used in certain countries, often in socially based systems of racial classification or of ethnicity, to describe persons who are perceived to be dark-skinned compared to other given populations. As such, the meaning of the expression varies widely both between and within societies, and depends significantly on context. For many other individuals, communities and countries, "black" is also perceived as a derogatory, outdated, reductive or otherwise unrepresentative label, and as a result is neither used nor defined. 

No
Black people is a term used in certain countries
derogatory, outdated, reductive or otherwise unrepresentative label
 "black" is also perceived as a derogatory, outdated, reductive or otherwise unrepresentative label, and as a result is neither used nor defined. 
persons who are perceived to be dark-skinned
 persons who are perceived to be dark-skinned 
Yes
 to describe persons who are perceived to be dark-skinned compared to other given populations
North America
, in North America the term black people is not necessarily an indicator of skin color or majority ethnic ancestry, but it is instead a socially based racial classification related to being African American, with a family history associated with institutionalized slavery.
not necessarily
 in North America the term black people is not necessarily an indicator of skin color 
South Pacific regions
mixed-race people are generally not classified as "black." In South Pacific regions such as Australia and Melanesia
societal variables affect classification as much as skin color
societal variables affect classification as much as skin color, and the social criteria for "blackness" vary.
South Pacific regions
In South Pacific regions such as Australia and Melanesia, European colonists applied the term "black" or it was used by populations with different histories and ethnic origin.