Overstay:

When visitors enter the United States on a visa, the DHS U.S. immigration inspector gives them a white card called an Arrival-Departure Record, Form or I-94.  On this card the DHS, the U.S. immigration inspector records the length of time that visitors are permitted to stay in the United States.  If the visitor stays longer than what the DHS permitted him/her to stay, he/she is considered an overstay.  The visitor may not be able to get another visa, depending on how long he/she overstays the visa.