This page shows images of immigrant visas and talks about certain aspects of them.
A visa is an authorization for an alien to enter and stay in the United States which is affixed to the foreign passport of the alien. It is issued under the authority of the Department of State, usually at a consulate or embassy located in a foreign country, which is typically the country of residency or citizenship of the alien. If the purpose of the entry is to establish permanent residency, then the visa is an immigrant visa. If the purpose is a temporary stay in the United States, then the visa is a non-immigrant visa.
The images on this page represent immigrant visas. The first is a type of immigrant visa that first was issued in 2003. When a person enters the US on such an immigrant visa, the visa itself is stamped with an ADIT stamp. This endorsement acts as immediate but temporary proof of permanent residency for a year, pending receipt of a more permanent resident card, and is valid for employment authorization. (Upon receipt of the permanent resident card card, any form I-9 issued initially on the basis of the immigrant visa must be reverified.) Later versions have the ADIT stamp printed into the visa as a security protection. This image is of the more recent type of ADIT stamp.
The second image is the earlier version of the immigrant visa with ADIT. The large yellow arrows show where the ADIT stamp is located.
There is another type of stamp that local USCIS offices sometimes will agree to put in a foreign passport as temporary proof of permanent residency pending receipt of a delayed permanent resident card, see green cards (second image).