Dates are significant because they indicate when particular occurrences occur. This is critical because history is written in chronological order. It is useful to know that one event occurred before another so that the link between events may be examined. Historians use dates to represent eras. For example, we say that Napoleon ruled France from 1799 to 1815 or that World War I began in 1914. These dates tell us when particular events occurred. Dates are also important because they can help identify the source of information. If we know that an event occurred on a certain date, we can assume that any information about it that comes after this date was not obtained from first-hand experience but rather from other people who were there or who heard about it later. For example, historians can estimate that Martin Luther nicked his 95 Theses against the Use of Indulgences by October 31st, 1517 because documents mentioning this event start appearing around this time. They know this because this is when he posted these documents publicly -– something he had never done before. In conclusion, dates are important because they can help historians understand what happened over 100 years ago and also what is happening today.