A citizen of a foreign country who wishes to enter the United States must first obtain a visa, either a nonimmigrant visa for a temporary stay, or an immigrant visa for permanent residence. Visitor visas are nonimmigrant visas for persons who want to enter the United States temporarily for business (visa category B-1), for tourism (visa category B-2), or for a combination of both purposes (B-1 / B-2). A foreign citizen needs to meet the following eligibility conditions to get a Visa to USA:

• The applicant must have a passport that is valid for a period of at least 6 months.
• You should not have any past history of crimes or should not have any criminal
  case ongoing cases against them.
• Dependents / spouses travelling with the applicant should apply for separate
  Visas.
• The applicant should have enough finance to support himself and dependents.
• The applicant should have a sound health and needs to go thorough medical test
  by approved physician.
• The applicant should have strong ties with his/her current country of residence.
• You should have a valid reason for travelling to the United States
  A consular officer will interview you to determine whether you are qualified to receive a
  visitor visa. You must establish that you meet the requirements under U.S. law to receive
  a visa.