Black Friday is a casual term for the day following Thanksgiving Day in the USA, the 4th Thursday of November, that has become considered the start of the country's Xmas shopping and eating season ever since 1952, while the phrase "Black Friday" could not come to be broadly well known or even utilized until the early on the 2000s.
Note: In Arab Counties, they are calling it "White Friday".
According to Calendarz.com, Black Friday 2021 was on Friday, November 26th.