It's Black History Month in the UK, a time of celebration, reflection, and education.
Now, it may seem a fairly cut-and-dry concept - to uplift and commemorate black people, black history, and black achievements. But have you ever thought about what it actually means to be "black"? Who are we actually celebrating? Who counts as "black"?
And no, these are not trick questions.
In the UK specifically, black people made up 3.3% of the population, according to the last census carried out nearly a decade ago in 2011.
Of this 3.3%, 1.8% ticked the "Black African" box, 1.1% ticked "Black Caribbean", and 0.5% ticked "Black other".
The unifying factor of all these groups is a shared Sub-Saharan African heritage.
Sub-Saharan African countries are essentially those outside of the predominantly Arab region of North Africa.
So, in essence, being "black" means being of Sub-Saharan African descent. But it's not always as simple as that...
Today, "black" can be better described as an all-encompassing label. A label that's not entirely about your actual genetic makeup. But instead, it's a combination of your genetic makeup and, crucially, how you're perceived and categorised in society as a result.
In some ways, it's a very subjective racial category, based on perception as opposed to a classification based on someone's full ethnic background.
In many Western countries - and, indeed, in most places outside of Sub-Saharan Africa - anyone with any visible African descent is "black". Or in the case of someone like Kamala Harris, any known African descent.
When Harris, who is of Jamaican and Indian parentage, was named Joe Biden's pick for Vice President, she became the "first black female running mate."
This was due to known information about her Jamaican father as opposed to any "obvious" black heritage.
In the US especially, the black part of someone's heritage is typically regarded as the defining aspect of their race.
For example, Beyoncé, who is of partial African descent, is regarded as black in much the same way as Kenyan actress Lupita Nyong'o.
In countries with an equally complex history with race - such as Brazil - racial categorisation is actually very different.
Bear in mind, during the transatlantic slave trade, Brazil imported more African slaves (about 4 million) than any other country. These 4 million African slaves made up around 40% of all slaves brought to the Americas.
In comparison, only about 388,000 slaves were shipped to North America. This is despite the fact that the discourse around the transatlantic slave trade often focuses on slavery in the US.
To this day, the South American country has the largest number of people of African descent in any country outside of Africa.
This is an example of what is known as the African Diaspora. The African Diaspora was the historically forced movement of black Africans to various parts of the world - namely the Americas.
Although, these days, it can also refer to the people of African descent who willingly choose to migrate to other parts of the world.
As mentioned above, 40% of African slaves were forcibly transported to Brazil, less than 5% were taken to North America, and the remaining 55% accounts for the forced movement of people to the Caribbean and other parts of the Americas.
In Brazil, due to its long history of what was then known as miscegenation (race mixing), a large proportion of the country's population is of mixed race.
However, there are clear physical differences between "white Brazilians" (who may or may not have some African ancestry), and "black Brazilians" (who may have some European ancestry).
And then there are the "Pardo" or mixed-race Brazilians (who usually have a fairly equal split of African, European, and indigenous ancestry).
As an indicator of just how mixed Brazil is, in its most recent census of 2010, 43.1% of the population ticked the "mixed-race" box.
The 2010 US census, on the other hand, did not include any specific categories for people of mixed race.
South Africa, like Brazil, also has a culture of differentiating between black and mixed-race people. In South Africa, mixed-race people (known as "coloured people"), tend to be of a mix of African, European descent, and sometimes Asian descent.
According to South Africa's last census of 2011, 8.9% of its population identifies as coloured.
The largest group of European settlers came from the Netherlands, having arrived in the country around 1652. And so the heritage of South Africa's coloured people often - but not always - includes Dutch as well as South African ancestry.
European heritage from France, Germany, and Britain is also common in South Africa's mixed-race communities.
In many Hispanic countries such as Puerto Rico, Colombia, and Venezuela, people tend to have varying amounts of African ancestry - again, due to the African diaspora.
However, because "Hispanic" is often spoken about as though it were a race in itself - rather than a combination of origins - very few people are aware of this.
In light of this, there are some ways in which the standard definition of what it means to be "black" (that is, of African descent) gets tricky.
For example, Bruno Mars who is of partial Puerto Rican parentage has sometimes been accused of "appropriating black culture".
As part of a discussion on cultural appropriation on web show, The Grapevine, writer Seren Sensei criticised the star, saying that he "100% is a cultural appropriator. He is not black, at all, and he plays up his racial ambiguity to cross genres."
And yet, Mars' Puerto Rican roots mean that he could have some African ancestry - as does the average Puerto Rican.
In fact, according to an article on National Geographic, the "average Puerto Rican individual" carries "20% Sub-Saharan African DNA."
It's just that, in Mars' case, his African ancestors - if he does indeed have African ancestors - would have been taken to Puerto Rico rather than the US during the transatlantic slave trade.
His ethnic background aside, the '24K Magic' singer grew up listening to historically African American genres such as jazz, Motown, and funk.
No one should be shamed for appreciating and being inspired by a genre of music just because it was created by people who may have different ethnic origins to them.
Mars was raised in a culture steeped in black history, and there's no denying that he credits the communities that inspired his career.
In fact, in 2017, he told Latina magazine, "When you say 'black music,' understand that you are talking about rock, jazz, R&B, reggae, funk, doo-wop, hip-hop, and Motown."
He continued, "Black people created it all. Being Puerto Rican, even salsa music stems back to the Motherland [Africa]. So, in my world, black music means everything. It’s what gives America its swag."
We have to ask ourselves: Does the standard definition of "black" (that is, of African descent) hold true in each and every circumstance?
Or is there one rule for how someone like Kamala Harris is perceived and another for Bruno Mars?
Is Harris’ African ancestry any more valid because it stems from Jamaican as opposed to Hispanic roots?
And exactly how much African heritage do you have to have to count as black?
The truth is, "black" is not a fixed and objective racial category. It differs depending on the culture and history of a particular country, and its overall demographics.
What might be considered undoubtedly black in the UK or the US might not necessarily be considered black in the Dominican Republic, for example.
It's up to individual cultures, subcultures, countries, cities, neighbourhoods, and, of course, people to decide who they instinctively regard as being "black".
But just bear in mind that this perception might not always align with a person's entire ethnicity, ancestry, background, and, crucially, how they personally choose to identify.
In that sense, blackness is unique.