Just What are J 1 Exchange Visitors?

http://exchanges.state.gov/jexchanges/programs/swt/pdfs/j-1-swt-program-for-ca-mtg-with-sponsors.pdf

J-1 Exchange Visitor Visa General Information:

The United States government issues J-1 Visas to individuals who take part in a wide range of exchange visitor programs sponsored by schools, businesses, and a variety of organizations and institutions. These programs are envisioned for business and industrial trainees, scholars, students, international visitors, teachers, research assistants, and those on cultural missions. In addition, there are several exchange visitor programs for young people, including summer employment programs, internship programs for university students and au-pair programs.