If you find a birth certificate issued by the government, this is a primary source. The information for the certificate was given by the parents of the child and the hospital in most cases. The same is true for marriage certificates. Death certificates are not totally primary sources however since the person giving the information about parents is not the deceased but rather a family member.
A primary source should be created at about the same time as the event being recorded. This in a death certificate, the date of death is a primary source but the other information is a secondary source.
A family bible with entries that were created at the time they occurred can be considered a primary source but events not recorded at the time they occurred are secondary.
Censuses provide great information but since until 1940 we don't know who is providing the information, they must be considered secondary sources. A will is often a great primary source.
When it comes to accepting dates and information, a primary source can be accepted but always try to have at least two secondary sources for anything you want to accept as truth. That this is not always possible, which is one of the things that makes genealogy so difficult.
When in doubt, try to figure out who provided the information and that will let you know how close to the truth it actually is.
- Birth certificates
- Baptism certificates
- Marriage certificates
- Death Certificates
- Census information after 1940
- Family bible (if the entries were made at the time the event occurred)
- Will or inventory
- Military record
- Naturalization documents