Here's why:
* Titles are not complete sentences. They are generally phrases or short statements that capture the essence of the essay's topic.
* Periods are used to mark the end of a complete sentence. Since titles are not sentences, they do not require periods.
Exceptions:
* If a title ends with an abbreviation. For example, "The History of the U.S.A." would have a period after "U.S.A."
* If the title is a question. In this case, the question mark replaces the period.
In general, it's best to avoid using periods in your essay titles unless absolutely necessary. This will help ensure your title is clear, concise, and grammatically correct.