Business travelers may enter the United States using a B1, or ‘Visitor for Business’ Visa. In practice these visas are invariably issued as jointly with B2, or ‘Visitor for Pleasure’ (i.e. Tourist) visa. This practice means that, if a candidate has an old tourist visa, it may be valid for a planned business trip. For those who come under the visa-waiver scheme, details of which are provided below, there is usually no need to apply for a visit visa at all if the candidate wishes to visit the US for three months or less.
Obviously there is a considerable ‘Gray area’ in between what definitely is allowed and what definitely isn’t. It is advisable to err on the side of caution when bringing overseas persons into the USA on business visitor visas. However, in certain strictly limited cases, paid employment may be possible using a 'H1B’