(A) Some nonimmigrant visas prohibit employment in the United
States. Tourists and business visitors, for example, may not
work at all.
(B) Some nonimmigrant visas require the foreign national to
obtain a special documents evidencing employment authorization
from the Immigration and Naturalization Service before working.
This is called an Employment Authorization Document (EAD).
This type of employment authorization is temporary.
(C) Some nonimmigrant visas automatically grant employment
authorization, and do not require any additional documentation.
Foreign nationals holding H-1B, L-1 or E status fall into
this category. This type of employment authorization is temporary
and job-specific.