Many businesspersons travel to the US using a B1/B2 visa or a visa waiver system (eg, ESTA).
However, for a number of business travelers, their purpose of travel may not be authorized by a B1/B2 visa. Or that person may not qualify for travel under a visa waiver program.
In such instances either a B1 or “B1 in lieu of H” visa may be the right solution.