Your Immigration Document
Your DS-2019 is the immigration document that demonstrates your legal status and presence in the United States. It is created by either the University or your Sponsor upon your admission and you must maintain it for the duration of your J-1 status.
Your DS-2019, along with your passport, is your most important immigration document while you are in the States. It is very important to keep it current and to get it properly signed before traveling outside of the U.S.
If you have any dependents, they will also be given DS-2019s. Their statuses are dependent upon yours, and they also must get travel signatures if they plan to leave the United States and reenter.