In contemporary social science, race is understood as a social construct rather than a biological fact. This means that different societies created, defined, and gave meaning to racial categories.
A social construct is an idea or category that exists as a result of people recognising and reinforcing it collectively.
In terms of race we see that:
Different societies classify people into different racial categories.
Racial categories change historically.
Social meanings of race are historically constructed.
An example of this concept is the changing definition of “Whiteness” in the USA in the last two centuries.
From the biological perspective:
Modern genetics shows that we share 99.9% of our genes as human beings.
There are no distinct biological races of humanity.
There is more genetic variability within racial groups than between them.
Even if there are some variations in genes (e.g. skin color) racial categories cannot be formed.
From the sociological perspective:
There have been studies proving that race is a social construct, as people assign meanings to physical features such as:
Skin color.
Hair texture.
Facial features.
These meanings have an impact on:
Identity.
Social status.
Access to social, economic, and health resources.
Consequently, race establishes how society operates.
Similarly to race, ethnicity is socially defined.
However, while race is based on physical appearance, ethnicity refers to cultural characteristics.

Some famous scholars stressing the social construction of race include:
W.E.B. Du Bois.
Michael Omi and Howard Winant.
Ashley Montagu.

Read More:

The Concept of Ethnicity