Applying for an immigrant U.S. visa from India involves several steps. First, determine the appropriate visa category based on your eligibility, such as family-based, employment-based, or diversity visa. Your U.S.-based sponsor (family member or employer) must file a petition on your behalf with the United States Citizenship and Immigration Services (USCIS). Once approved, the case is forwarded to the National Visa Center (NVC) for processing. The NVC will request supporting documents, including your passport, photographs, civil documents (like birth and marriage certificates), and financial evidence. You must then complete the DS-260 Online Immigrant Visa Application and pay the associated fees. Following this, schedule a medical examination with an authorized physician and attend an interview at the U.S. Embassy or Consulate in India. Bring all required documents, and be prepared to answer questions about your application. If approved, you will receive a visa stamp in your passport, allowing you to travel to the U.S. as a permanent resident.