Googles.
Ngram Viewer is a search tool that students can use to explore the use of words and names in books released between 1800 and 2019. The Ngram Viewer shows users a chart showing the very first appearance of a word or name in literature and the frequency with which that word or name appears in literature since 1800. The graph is based upon the books and regulars that are indexed in Google Books.

By the way, the book that I pointed out in the video is That Wild Country by Mark Kenyon..

Ngram Viewer is a search tool that students can utilize to check out the use of words and names in books released in between 1800 and 2019. The Ngram Viewer reveals users a graph showing the first look of a word or name in literature and the frequency with which that word or name appears in literature since 1800. The Ngram Viewer will let you compare the usage of several words or names in one chart.

The Ngram Viewer will let you compare using numerous words or names in one chart. The example that I give in this video is to compare using the terms “National Parks,” “National Forests,” and “National Forest Service.” By taking a look at the Ngram Viewer for those terms I can see that they begin to appear more often around 1890, have a lull in the 1940s and 1950s, and then appear more often once again in the 1960s..
Ngram Viewer is based upon books indexed in Google Books. That is why listed below every chart generated by Ngram Viewer you will find a list of books about each of your search terms. Those books are arranged by date..
A 3rd part of Ngram Viewer to keep in mind is that it deals with numerous languages including English, French, Chinese, German, Italian, Russian, Hebrew, and Spanish..

Applications for Education.
As I discussed in the video above, the Ngram Viewer can provide an excellent way to begin a research study activity for trainees. Have them go into a couple of words then take a look at the graph to determine peaks and valleys in the frequency of the words use. Then inquire to attempt to identify what would have caused those words to be utilized more or less often at different periods in history.