The B-1/B-2 visa is used for short-term visits for business (B-1) or pleasure (B-2). It is usually difficult to change from this visa category to one more appropriate for a foreign scholar while in the U.S. If such a change is allowed, the USCIS may take several months to grant a decision, during which time paid employment is not allowed. No paid employment is permitted on the B-1/B-2 visa.
The law allows individuals holding B-1 or B-2 status as well as those participating in the Visa Waiver Pilot Program (see below) who hold either W/T or W/B status, to accept honoraria in addition to reimbursement for expenses provided that they do not spend more than 9 days at an institution. Individuals receiving honoraria are limited to 5 visits in a 6-month period of no more than 9 days at each institution. * There is no limit on the amount of the honoraria. If a scholar stays at one institution for a longer period of time, he/she is not eligible for an honorarium and may only be reimbursed for expenses. Visitors should have a letter from the inviting department explaining their activities, and detailing payment. Although not required by law, it is very important that these short-term visitors have adequate health insurance for their stay in the U.S.
*If the individual is not receiving honoraria, there is no limit to the number of institutional visits permitted.
The Department of State created the Visa Waiver Program to allow citizens of certain countries to enter the U.S. for a brief visit without obtaining a B-1/B-2 visa stamp at a U.S. Consulate or Embassy abroad. Visitors to the U.S. may use the Visa Waiver Program only when they are staying for less than 90 days and when they hold a return air ticket. Individuals who enter the U.S. on the Visa Waiver Program are not eligible to extend their stay in the U.S. or to change to a different non-immigrant status. Please consult an advisor in the HIO before recommending this program.
Since June 26 2005 individuals visiting the US using the Visa Waiver Program have been required to possess machine readable passports (biometric passports will be required by October 2006). Individuals who do not have passports that meet the current requirements may not enter the US using the Visa Waiver Program. These individuals must apply to a US embassy or consulate for a B Visitors Visa.
Read about passport requirements here: