A certified copy of a birth certificate is a document that has an official state registrar’s raised, embossed, impressed or multicolored seal, the registrar’s signature as well as the date the certificate was filed with the registrar’s office, which has to be within one year of the person's birth.
Along with U.S. Passports, Certificates of Citizenship and Certificates of Naturalization, certified copies of birth certificates are one of the most common documents used to prove citizenship and one of the four main vital records in a person's life (together with death, marriage and divorce records).
At a point in time it is likely that you will need a certified copy of the birth certificate as a form of identification, like obtaining a US passport or applying for Social Security benefits. Copies of a birth certificate can be obtained through the office where the document was originally filed or issued.