| Category | Source Type | Advantage | Disadvantage
|
Primary Source or
Original Source | Governmental, Church, and Organization, and personal records contemporary with the event | Highly accurate | Even contemporary records by the participants sometimes err.
|
| Recollections of persons who witnessed events | Often highly accurate accounts
| Sometimes subject to information loss or corruption because considerable time may have elapsed between the event and when the eyewitness described it.
|
| Secondary Source or Derivative Source | Corporate Entity WebSite | Contain a wealth of information, usually sourced, Usually verifiable, usually not validated | Often contains a mix of verifiable and unverifiable information, sometimes contains unsourced information (e.g., Ancestry Family Trees)
|
| Recollections of persons who knew persons contemporary with the events | Often contain accurate information obtained first hand from eyewitnesses | Often contains misunderstandings. Potential for information loss is moderate.
|
| Published histories, biographies. | Often contains well distilled information based on primary sources | Sometimes contains unsubstantiated opinion.
|
| Mixed* | Published Family Genealogies | Focused on specific lineages; typically contains a mixture of sourced and unsourced materials, sometimes contains transcripts, extracts, or abstracts of original source material; Contains conclusions based on interpretation of information developed from a mixture of primary, secondary sources that may offer considerable insight into the family history | The authors conclusions are usually interpretative, and subject to interpretational error. Where primary and secondary sources are not cited, what they say is not verifiable, and the are best treated as tertiary sources.
|
| Tertiary Source | GEDCOM | Can be used to rapidly increase size of family tree, or to add information to individual cards in that tree | Usually unsourced, unverifiable, unvalidated; a well documented GedCom, relying on at least secondary sources to document conclusions reached, can rise to the level of a secondary source. However, as an Ephemeral Source a GedComcan not be relied on in the same way as secondary sources.
|
| Private WebSite | Often contain a distilled dicussion of family relationships and history | Often unsourced, unverifiable, unvalidated, and ephemeral. Can rise to the level of a secondary source, but as an Ephemeral Source can not be relied on in the same way as secondary sources.
|
| Emails and Letters by Genealogists | Often contain distilled summaries of information providing useful clues to the researcher | Everyone makes mistakes. Such items may not be available for other researchers to examine.
|
