A J1 visa is issued to a student who needs to obtain practical training, which is not available in their home country, to complete their academic program. J1 visas are also available for work and travel programs. Because students on J1 visas are often able to earn enough money to pay for their entire stay, the J1 visa program has become very popular.
J1 visas require an official "sponsoring organization" which has been designated and approved by the US State Department. Sponsors can be private or public organizations. Private, for-profit J1 Work and Travel operators have multiplied, making it difficult to sort through to find the best program. For a fee, these programs will get you a J1 visa, get you a job, provide health insurance and sometimes travel and lodging. There are many good and respected J1 visa operators, but some have provided sub-par experiences to their participants, and it pays to do your research.
This visa enables applicants to enter the U.S. to participate in an Exchange Visitor Program. It may be an option for trainees, students, professors, or research scholars, physicians and summer students in travel/work programs. Traditional college and university students are typically on F1 visas, not J1 visas, though research scholars and visiting professors may be J1. The period of stay differs according to the different categories - most Work and Travel programs are three to four months, and most trainee/internship programs are up to 18 months. Spouses of J-1 applicants may be employed provided employment is not for the support of the J-1 and the spouse is not a J-1 visa holder themselves. Employment may be authorized for the duration of the J-1 validity or 4 years, whichever is shorter.
Jobs available on campus typically do not pay much, certainly not enough to finance a university education. Do not count on this kind of a job for anything more than a supplement to other funds. J-1 student status allows for similar employment, with similar restrictions, as long as permission is given by the exchange visitor program sponsor.
Since J1 visas are only issued through sponsoring organizations, your sponsoring organization (whether a work and travel operator, a trainee program, or a university) will help you through the process of obtaining your J1 visa.