Visa - A visa is the actual stamp in your passport by a US consulate or embassy. It will indicate the number of times you may enter the US and an expiration date. A visa does not need to remain valid once you are in the US, but must be valid (in the proper classification and for Wittenberg) if you leave the US and wish to return. Think of it as your entry ticket.
Status/Permission to stay (F or J)- This indicates your legal permission to remain in the US. This must be valid. If you have a visa marked D/S (duration of stay), this means that you are in status as long as you are a full time student and observe all other regulations.
To remain in status you must: