As you research the lives of your ancestors you may become too focused on finding dates and locations for events, and forget about the "big picture" -- world and local events, circumstances, and surroundings which probably have some sort of impact on that ancestor. That's where a timeline comes in handy. Timelines serve to remind us of what events happened in relation to a person's life. You can compare the ancestor with a historical timeline of events, compare the ancestor with another ancestor, figure out who may have moved due to major events (the Potato Famine, the Gold Rush, military actions, expansion of borders, etc.), which ancestor was old enough (or too old) to serve in which war, and so on.

Creating a timeline shows researchers not only what events may have influenced their ancestor's lives, but also what avenues might be explored, and what resources were not available. For instance, there is no sense in looking for 1850 records for Washington State, because the state wasn't a territory until 1853. A good timeline will point out which resources may or may not have been available for a particular ancestor.

You can create a timeline yourself or you can use the timeline function of many genealogy programs to create a timeline based on data you entered. Timelines can be strictly a list of historical events, a list of individuals in your family arranged in chronological order, or a combination of the two.