The Visa Waiver Program allows citizens of certain countries to travel to the United States for tourism or business purposes for stays of 90 days or less without obtaining a visa. Travelers must apply for authorization through the Electronic System for Travel Authorization (ESTA) before their trip.

To apply for a US visa, you typically need to complete a nonimmigrant visa application form (DS-160), schedule an interview at the US embassy or consulate in your country, pay the application fee, and provide supporting documents such as a valid passport, passport-sized photos, and evidence of ties to your home country.

Processing times can vary depending on the type of visa and the workload at the embassy or consulate where you apply. Generally, it can take anywhere from a few days to several weeks or even months to process a US visa application. It’s advisable to apply well in advance of your planned travel date.

If you plan to study or work in the United States, you will likely need to apply for a specific type of visa, such as an F or M visa for students, or an H-1B visa for temporary workers in specialty occupations. The requirements and application process vary depending on the type of visa you need.

It may be possible to extend your stay in the United States under certain circumstances, such as for tourism, business, medical treatment, or to continue studying or working. However, you must apply for an extension before your current visa expires and meet the eligibility criteria for the extension.