Why is it called the Gilded Age?

The term “Gilded Age” comes from the late 19th-century United States and originates from the title of the book The Gilded Age: A Tale of Today by Mark Twain and Charles Dudley Warner, published in 1873.

The term “gilded” refers to the process of covering the surface of something with gold, typically stone, wood, porcelain, or metal. The use of the term $\text{\textquotedblleft}$Gilded Age" to describe the period in the US is a metaphor for the social and economic conditions of the time. While there was rapid economic growth, industrial expansion, and incredible generation of wealth during the era, it was the “gilding” that covered up the underlying social problems in society during the time, including pervasive government corruption, deep inequality, and poverty.

Thus, the term is intended to denote an era in which the brilliant façade of society was merely a mask for profound social and economic flaws.