The term "Manifest Destiny" refers to a belief or ideology that emerged in the 19th century in the United States. It was the idea that it was the destiny, or fate, of the United States to expand its territory and spread its values, institutions, and way of life across the entire North American continent.

The concept of Manifest Destiny was rooted in the idea of American exceptionalism and the belief that the United States was a uniquely virtuous nation with a special mission to fulfill. Supporters of Manifest Destiny saw the expansion of the United States as a natural and inevitable process that was justified by a divine right or a sense of superiority over other nations.

This ideology fueled the westward expansion of the United States, leading to the acquisition of vast territories such as the Louisiana Purchase, the annexation of Texas, the Oregon Territory, and the Mexican Cession. It also played a role in the displacement and mistreatment of Native American populations as the United States expanded its borders.

Manifest Destiny was used as a rallying cry for American territorial expansion and was influential in shaping the country's foreign policy during the 19th century. However, it also had critics who questioned the moral and ethical implications of forcibly taking land from Native Americans and other nations.

Today, the concept of Manifest Destiny is seen as a controversial aspect of American history, highlighting the complex and often conflicting narratives of American expansion and its impact on indigenous peoples.