This article is from the FAQ, by with numerous contributions by others.
The L-1 visa category was established to facilitate the transfer
or rotation of foreign personnel of an international company into
the United States. Although originally targeted toward large U.S.
multinational corporations, this is an appropriate method for companies
of all sizes to seek immediate immigration benefits for their
qualifying employees. Further, the L-1 visa may provide quick access
to lawful permanent resident (immigrant) status in the United States.