I have always looked at an obituary as a celebration of an individual's life. An obituary will give you information of what that person did in his or her life and many of their accomplishments. For a family researcher, it can give you more information that will help you move to the next step in your search for that ancestors.
For the researcher trying to pinpoint that ancestor especially if this person was an immigrant ancestor, an obituary may also tell you when and where that person was born and when they arrived into North America. Even when the location of birth is somewhat generalized, it could narrow your search to a county or province of birth.
The obituary can also provide you with a date and location of your ancestor's marriage which can then lead you to a civil or religious marriage record. This additional information might help the researcher find additional information about that person's birthplace as well as the name of their parents.
Included with this blog are two obituaries that contain some valuable information for the researcher. The first obituary indicates that the ancestor was born in County Derry/Londonderry, Ireland along with the date. It also provides the month and year that this ancestor immigrated to the U.S.
Another example also shows not only the date of birth but also mentions, "near Londonderry," Ireland for the place of birth. This obituary also indicates when this ancestor came to the U.S. This information will allow the researcher to check the passenger ship lists and verify the date and locate the port of departure.
Your ancestor's obituary can also provide the religion they belonged to while in North America. This was, in many cases, the same or similar religion that ancestor practiced while in their native country. If the ancestor was Catholic in the U.S., chances are they were practicing that faith in Ireland. One could then check the Catholic records online at the National Library of Ireland or the government site at Irish Genealogy.ie.
The same would exist for those practicing the Protestant religions in North America. One could the check the Representative Church Body Library web site. Irish Genealogy.ie also has a link to civil records from Ireland.
Not all obituaries contain the information you are looking for and, in the case of large city newspapers, the information may be very general and not very useful. Also keep in mind, the information used in the obituary may be based on the memory of a family member which might not be totally accurate. So, an obituary is one piece to the family tree puzzle and you might need another source of information to verify all the details. But in many cases, an obituary can be a great source of information in following the life of an ancestor and determining their place of birth.