DHS = Department of Homeland Security.
DOS = Department of State, the overseeing department of U.S. embassies and consulates abroad.
DS-2019 = The immigration document for students and visiting scholars in J-1 status.
Form I-797 = After an H-1B petition is approved by USCIS a Form I-797 H-1B approval notice (Notice of Action) is issued and sent to EIS. This document indicates the H-1B employer and the dates of the approved H-1B status.
I-20 = The immigration document for students in F-1 status.
I-94 Card = This is usually a small white arrival/departure card. It shows that the status held is H-1B and it indicates the current end date of the H-1B status. (The H-1B approval will include a new I-94 card.)
USCIS = United States Citizenship and Immigration Services, a branch of Department of Homeland Security.
USICE = United States Immigration and Customs Enforcement, a branch of Department of Homeland Security.