Why did mark the Twain and Charles warner call the late 1800s the gilded age?

Mark Twain and Charles Warner coined the term "Gilded Age" in their 1873 book to describe the late 19th century in America. They used "gilded" to suggest that, while the era appeared prosperous and glittering on the surface, it was actually marked by significant social issues, corruption, and economic disparity. The term highlights the contrast between the glamorous façade of wealth and the underlying problems of inequality and moral decay. Ultimately, it critiques the illusion of progress during a time of great societal change.