The United States visa waiver scheme is specially designed for 39 selected countries, which form the Visa Waiver Program. Following are the Visa Waiver Countries for the US tourist visa.
Citizens of countries that are not in the Visa Waiver program cannot obtain the ESTA, but may still visit the US by applying for a B1 work visa or a B2 tourist visa.
Applicants who are not part of the Visa Waiver Program may apply for a B1 work visa or a B2 tourist visa.
Successful B1 visa applicants will have the right to visit the United States for a period of 1-6 months (depending on the visa expiry date). Those granted the visa may participate in business-related activities such as conferences, negotiations, short-term training, conferences, etc.
Successful B2 visa applicants may travel to the US for touristic and leisure purposes.
Note that entering on a B2 visa does not grant the right to study or work while in the United States. Short-term courses are an exception to this rule, provided they are no longer than 18 hours per week.