ESTA (Electronic System for Travel Authorization) is a not so well-known automated system that was built to determine eligibility for people traveling to the US under VWP (Visa Waiver Program). The system is straightforward but since not much is known about it, most people make assumptions that are incorrect. One of the assumptions is that everyone needs an ESTA approval. In reality, you only need this in some specific situations. 

The US J-1 visa is a very interesting visa under the non-immigrant category. It is used to allow teachers, exchange visitors, and scholars to participate in US programs promoting cultural exchanges. In most situations, the visa is used to get business or medical training in the country, but other situations do apply. Applicants have to meet strict eligibility criteria that are much stricter than the ESTA based visa waiver program.