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We find that the definition in Wikipedia is the easiest for everyone to agree with:
Pop-up restaurants, also called supper clubs, are temporary restaurants. These restaurants often operate from a private home, former factory or similar space, and during festivals.
Pop-up restaurants have been popular since the 2000s in Britain and Australia but they are not a new phenomenon. Pop-up restaurants have existed in the United States and Cuba. Diners typically make use of social media, such as the blogosphere and Twitter, to follow the movement of these restaurants and make online reservations.
Pop-up restaurants, like food trucks, are an effective way for young professionals to gain exposure of their skills in the field of hospitality as they seek investors and attention pursuant to opening a restaurant or another culinary concept.
Pop-up restaurants have been hailed as useful for younger chefs, allowing them to utilize underused kitchen facilities and “experiment without the risk of bankruptcy”. By 2013, this restaurant style had gained steam and prevalence in larger cities thanks in part to crowd-funding efforts that offered the short-term capital needed to fund start-up costs.