Details:
Generally, a citizen of a foreign country who wishes to enter the United States must first obtain a visa, either a non-immigrant visa for a temporary stay, or a migrant visa for permanent residence. Exchange visas (J-1) are non-immigrant visas for individuals approved to participate in exchange programs in the United States.
Exchange categories include:
- Au pair and EduCare
 - Short Term School 
 - Camp Counselor
 - Student, College/University
 - Internal
 - High School Student
 - International Visitor (Department of State)
 - Physicist
 - Professor and Research
 - Summer Work
 - Professor
 
Exchange Programs:
- Summer work/travel: Australians
 - Summer work/travel: New Zealanders
 - Intern work/travel: Irish
 - Work/en Study/Travel: South Koreans
 
How long does it take?
The entire process until you have a decision about your Visa should take around 4-5 weeks. (It may vary by country.)
How long can you stay?
The Exchange Visa allows you to stay within U.S. territory for the duration of your exchange program.