Actually, the distinctions between primary and secondary materials can get very blurry. Think about someone's autobiography, written many years after events had actually taken place. That person has had a long time to think about, analyze and interpret events and to exaggerate or "forget" certain details. While it is a firsthand account, it is probably not without some bias.
Now consider legal documents, forms which are filled out. Most, like a marriage certificate or birth certificate, are filled out and signed at the time of the event. These are clearly primary documents. But think about other forms you might fill out with information about your parents. You were not around when they were born, so data regarding their place and date of birth would be secondary information. A death certificate is generally considered both a primary and secondary source of information. The information relating to the death - time, place, cause, etc., is primary, but any information regarding the birth of that person is generally provided by a child or spouse, who was not around at the time to be an eye witness, so it is secondary information.
[an error occurred while processing this directive]