Your Guide to Genealogy and Dates
The careful genealogist pays a great deal of attention to dates. One of the first things we must learn is how to properly record them to avoid ambiguity... e.g. 9 Jan 2005.
We must learn how to calculate when we know a person's date at a specific age. We need to be aware of reasonable estimates and when to recognize that a date doesn't fit. For example, it is unlikely that a person lived 136 years or had a a baby at 67-- yet some genealogies have dates that indicate this is so.
We must know about calendar changes. The one that most commonly foils American researchers is the calendar change in 1752. In brief, prior to that New Years day was March 25 and the year did not change until that date. When the calendar changed to a January 1st new year, accomodations had to be made in the way dates were written to avoid confusion. Dates were designated O.S. (old style) and N.S. (new style).
There are some handy date converters for us on the internet that will allow us to determine a more exact date with incomplete information.
See the links below for more detailed information.