Timelines show the events of your ancestor’s life and where those events occurred. They can be important to direct your research and when you hit that brick wall (which you inevitably will), to focus on what might be missing. They show migrations allowing you to make sure you’re looking in the correct location for the records. They may also help you to distinguish two individuals of the same name.
The genealogical software I use (Reunion), creates a timeline from the events that have been entered. I save the document and open it in my spreadsheet application. Also, if you use an Ancestry online tree, the overview will provide a timeline. Most other software will also provide some type of timeline. The columns I use are: Age, Event, Location, Date and Comments.
While researching James Crofoot, I had identified him in the 1800 census in Newtown, Connecticut. When I looked at my information on James in a timeline, I discovered that in 1801 James was living in Salisbury, Connecticut, as identified in a land document, and in an 1832 affidavit for a Revolutionary War pension for his brother-in-law, Moses Tuttle, he stated that he knew him 40 years ago (1792) in Woodbury, Connecticut. This made me rethink the 1800 census record I had found. Originally it had seemed logical as the family had been lived in Newtown and Redding for many years, but it led me to other documents confirming that the James in Newtown was a different person.
Another use of timelines helps to narrow down the timeframe when searching for a record. I didn’t know when Michael Daly emigrated to the United States, other than he came through Ellis Island (1892-1924). There were 177 Michael Dalys in the Ellis Island database so how to determine which one was mine? By looking at a timeline of information I had collected on Michael, I new that in 1901 he was in Ireland (1901 census) and that he married in 1912 in Stamford, Connecticut. Also, he did not appear in the 1911 census of Ireland so that limited my search to the timeframe of 1901 - 1911 (and the number of Michael Dalys to about 80). By adding his birth year (± 2 or more years since the Irish were notorious for no knowing this information) I got down to 16 possibilities. The additional information collected after 1906 including the town he was from and his mother’s name, helped me isolate and confirm my Michael Daly arriving 3 Apr 1909. Another hint on timelines can be the birth of the children of a couple which can show the migration pattern of the family by showing when they were in specific locations.
I also add historical events to my timelines. Was your ancestor the correct age to have served in a war? If your ancestor was born between 1872 and 1897 and lived in the United States (whether a citizen or not) you should have a World War I Draft Registration. If your ancestor was an immigrant don't forget to add historical events from the country of origin.
If you haven’t been using timelines, give them a try. They may help to solve a longstanding research problem.