Black Friday is the day following Thanksgiving Day in the United States (the fourth Thursday of November).it has been regarded as the beginning of the Christmas shopping season in the US, and most major retailers open very early (and more recently during overnight hours) and offer promotional sales.

Black Friday also occurs in the United Kingdom. One of the UK’s first black Friday events took place in 2003 in Staples Corner London, hosted by UK retailer Currys

https://en.wikipedia.org/wiki/Black_Friday_(shopping)