Admission: 

Entry to the United States that is authorized by an U.S. immigration inspector (an employee of the DHS).  Admission or entrance into the U.S., by non-United States citizens, must be authorized by U.S. immigration at the port-of-entry.  U.S. immigration will determine if you can enter the country and the length of stay granted.  Once you are allowed to enter, the length of stay and immigration classification given are recorded with the Duration of Status (D/S) on Form I-94, Arrival-Departure Record, or Form I-94W, provided you are arriving on the Visa Waiver Program.  If you choose to stay longer that the date authorized, permission must be requested from the DHS’s BCIS.