Asian Americans are Americans with ancestry from the continent of Asia (including naturalized Americans who are immigrants from specific regions in Asia and descendants of those immigrants). According to annual estimates from the U.S. Census Bureau, as of July 1, 2024, the Asian population was estimated at 22,080,844, representing approximately 6.49% of the total U.S. population, making them the fastest growing and fourth largest racial and ethnic group in the United States after African Americans, Hispanic and Latino Americans and non-Hispanic White Americans.

Although this term had historically been used for all the indigenous peoples of the continent of Asia, the usage of the term "Asian" by the United States Census Bureau denotes a racial category that includes people with origins or ancestry from East Asia, South Asia, Southeast Asia, and Central Asia. It excludes people with ethnic origins from West Asia, who were historically classified as "white" and will be categorized as Middle Eastern Americans starting from the 2030 census. Central Asian ancestries (including Afghan, Kazakh, Kyrgyz, Tajik, Turkmen, and Uzbek) were previously not included in any racial category but have been designated as "Asian" as of 2024.

The "Asian" census category includes people who indicate their race(s) on the census as "Asian" or reported entries such as "Chinese, Indian, Bangladeshi, Filipino, Vietnamese, Indonesian, Korean, Japanese, Pakistani, Thai, and Other Asian". In 2020, Americans who identified as Asian alone (19,886,049) or in combination with other races (4,114,949) made up 7.2% of the US population.

Chinese, Indian, and Filipino Americans make up the largest share of the Asian American population with 5.5 million, 5.2 million, and 4.6 million people respectively. These numbers equal 23%, 20%, and 18% of the total Asian American population, or 1.5%, 1.2%, and 1.2% of the total US population. Vietnamese Americans are the 4th largest Asian American population, and Korean Americans are the 5th largest with both populations making up 8% of the Asian American population respectively.

Although migrants from Asia have been in parts of the contemporary United States since the 17th century, large-scale immigration did not begin until the mid-19th century. Nativist immigration laws during the 1880s–1920s excluded various Asian groups, eventually prohibiting almost all Asian immigration to the continental United States. After immigration laws were reformed during the 1940s–1960s, abolishing national origins quotas, Asian immigration increased rapidly. Analyses of the 2010 census have shown that, by percentage change, Asian Americans are the fastest-growing racial group in the United States.

As with other racial and ethnicity-based terms, formal and common usage have changed markedly through the short history of this term. Prior to the late 1960s, people of various Asian ancestries were usually referred to as Yellow, Oriental, Asiatic, Brown, Mongoloid, or Hindoo. Additionally, the American definition of 'Asian' originally included West Asian ethnic groups, particularly Turkish Americans, Armenian Americans, Assyrian Americans, Iranian Americans, Kurdish Americans, Jewish Americans of Middle Eastern descent, and certain Arab Americans, although in modern times, these groups are now considered Middle Eastern American and grouped under White Americans in the census. The term "Asian American" was coined by historian-activists Yuji Ichioka and Emma Gee in 1968 during the founding of the Asian American Political Alliance, and they were also credited with popularizing the term, which meant to be used to frame a new "inter-ethnic-pan-Asian American self-defining political group". This effort was part of New Left anti-war and anti-imperialist activism, directly opposing what was viewed as an unjust Vietnam War.

Prior to being included in the "Asian" category in the 1980s, many Americans of South Asian descent usually classified themselves as Caucasian or other. Changing patterns of immigration and an extensive period of exclusion of Asian immigrants have resulted in demographic changes that have in turn affected the formal and common understandings of what defines Asian American. For example, since the removal of restrictive "national origins" quotas in 1965, the Asian American population has diversified greatly to include more of the peoples with ancestry from various parts of Asia.

Today, "Asian American" is the accepted term for most formal purposes, such as government and academic research, although it is often shortened to Asian in common usage. The most commonly used definition of Asian American is the US Census Bureau definition, which includes all people with origins in East Asia, South Asia, and Southeast Asia. This is chiefly because the census definitions determine many governmental classifications, notably for equal opportunity programs and measurements.