These are NOT REQUIRED for international students, but you will most likely find it helpful. If you will be working at all -- whether on-campus, or eventually off-campus -- you will be required to get a social security number. The number you are given will remain the same for the rest of your life.
After your arrival and registration, you can make an appointment with the Immigration Advisor in the Office of the Registrar and she will supply the appropriate letter from the university requesting that you are given a Social Security Number. The laws regulating the Social Security Administration are changing, so you must see the Immigration Advisor as your first step.
In the meantime, feel free to see
http://www.ssa.gov/pubs/10181.html and
http://www.ssa.gov/ssnumber/ and study how SSN works. Download the application form for SSN at
http://www.ssa.gov/online/ss-5.pdf, print it, fill-in whatever you can, and bring it with you to your advising appointment and to the SS Office.
You can be a victim of privacy violations and identity theft if you do not carefully handle your SSN. Do not become a victim. Inform and protect yourself. Never carry your Social Security Card and a picture identification card together. If they are lost or stolen, then it is easier for someone else to steal your identity. See the following:
http://www.ssa.gov/pubs/ssn_1.html
http://www.ssa.gov/pubs/idtheft.htm
http://www.consumer.gov/idtheft/
http://caag.state.ca.us/idtheft/tips.htm