There are various types of certificates. One common certificate is a gift certificate. Many people get gift certificates for Christmas, put them in a drawer and forget them, but that doesn't mean they still can't be used. Under state laws, which vary by state, it may be illegal for businesses to place expiration dates on any gift certificate that was purchased for less than a certain amount. There may be an exception is for gift certificates that were donated.
Some schools offer certificates in specialized fields of study. These programs are designed for those who desire to upgrade skills in their occupational specialty or to acquire a certificate prior to a degree after high school.
Another example is a driving certificate. Driving certificate laws are governed by state laws, which vary by state. A state which authorizes a driving certificate allows temporary legal residents to carry a "certificate of driving" instead of a driver's license. This would allow the foreigner to drive, but could not be used as identification.
