Please make copies of your immigration documents and keep them in a safe place, separate from the originals. Copy the following documents:
Passport identification pages that have your picture and personal information, as well as official information (including its date of expiration). If you have subsequently renewed/extended your passport, make sure that you copy the page with the extension information.
Passport page with your visa stamp on it
Both sides of your Form I-94
Both sides of your I-797 approval notice
Your passport is your own government's permit for you to leave and re-enter your own country. You should keep your passport valid at all times. Consult your own consulate or embassy in the U.S. to renew your passport at least six months before it expires. The consulate officials will tell you what forms and fees, if any, are required. You can link to Washington, D.C. embassies to obtain contact information for your country's nearest consulate. U.S. regulations require that your passport be valid for at least 6 months beyond your anticipated stay in the U.S.
The visa stamp placed in your passport by the U.S. consulate is needed to enter the United States, but has no bearing on how long you can remain. It also indicates the immigration classification you will have when you are admitted to the United States (e.g., O-1). You must renew your visa if it has expired and you are planning on traveling outside the U.S. You may renew your visa by visiting the U.S. Consulate in the country to which you are traveling.
If you are not going to your home country, be sure to consult with the U.S. Embassy or Consulate in the country you are visiting prior to leaving the U.S. to be sure you can obtain an appointment and renew your visa there. Visas cannot be renewed inside the U.S. For instructions on setting up an appointment and documentation requirements for applying for the O-1 visa stamp, visit the particular web site of the U.S. consulate you plan to visit when applying for the O-1 visa at List of U.S. Consular Offices worldwide.
The I-94 shows that you have been admitted to the U.S. The I-94 is usually stapled onto the U.S. visa page of your passport. It contains an eleven-digit identifying number (called your departure number) that the USCIS uses to keep track of your arrival in and departure from the United States. The USCIS sometimes refers to the "departure" number as the "admission" number.
There will be a date written in the upper right corner of your I-94. You must either leave the U.S. by that date or apply to extend your stay at least six months in advance. If you have changed to O-1 status within the United States, you will have received a new I-94 card attached to the bottom of the Form I-797 approval notice. This supersedes the I-94 card you received when you entered in your previous status.
The Form I-797 approval notice indicates that USCIS has approved the O-1 petition that was filed on your behalf. If you applied to change status in the U.S., there will be a be a new I-94 card attached to the bottom of Form I-797A. Otherwise, the form will indicate the consulate which has been sent notice of the petition's approval (Form I-797B). The form will also show the dates that the O-1 petition is valid.