There are two predominate meanings: the Census Bureau definition includes the Indian subcontinent along with East and Southeast Asia. The vernacular excludes the Indian subcontinent, though perhaps less so among the Indian community.
Afghanistan would not be included in either definition. Someone of Afghanistan ancestry (I'm purposefully avoiding distinguishing the various ethnicities in Afghanistan) would be classified as either Middle Eastern or Caucasian under the census definition as well as in the vernacular.
Right but what I'm getting at is that when people talk about "Asian Americans" in the context of college admissions, it seems like a coded way of talking about people of Chinese descent and not e.g. Filipinos.
Afghanistan would not be included in either definition. Someone of Afghanistan ancestry (I'm purposefully avoiding distinguishing the various ethnicities in Afghanistan) would be classified as either Middle Eastern or Caucasian under the census definition as well as in the vernacular.