Marriage records are primary source records because they are completed close to the time of the marriage by someone who was present at the marriage. They are important because they provide proof of a marriage as well as providing the maiden name of the bride.
There can be 3 main types of records
Marriage License - A bride and groom obtained a license to be married by applying to the proper authorities. These records usually have the most information of genealogical value, including the couple's names, ages, residences, race, birth dates, occupations and usually the names and maybe even birthplaces of the parents.
Marriage Register - After the ceremony, the signed marriage license was returned to the clerk for recording in a register or book. The information on the marriage usually included the names of the couple, the date and place of the marriage, and the name of the person who performed the marriage.
Marriage Certificate - The individual who performed the ceremony may have given the couple a physical certificate of marriage upon completion of the ceremony. The information on such a certificate varied, but always included the couple's names, marriage date, and location. This certificate is usually the hardest marriage record to locate as copies were not often kept by officials, though some original marriage certificates do exist in various records repositories and archives.