A Non-Resident Alien (NRA) is an individual who is not a citizen or permanent resident of a country, typically the United States, and does not meet the criteria for residency based on the number of days spent in the country. NRAs are often foreign students, temporary workers, or tourists who are in the country for a limited time. In the context of U.S. tax law, NRAs are subject to different tax rules compared to residents. They are generally taxed only on their income from U.S. sources, while their foreign income is not subject to U.S. taxation. Understanding this classification is important for compliance with IRS regulations.