Final answer:
The major developments during the Gilded Age included corruption and corporate domination, industrialization, and advancements in technology.
Step-by-step explanation:
The Gilded Age, a period during the late 19th century, was marked by several major developments. One of the key developments was the increase in corruption and corporate domination, which led to a growing suspicion of corporations and financiers. Another major development was the growth of industrialization, which significantly increased the population and economic size of the United States. Additionally, there were advancements in technology, such as the invention of the telephone by Alexander Graham Bell and the pioneering work in electricity by Thomas Edison.