It appears ngram is a simple frequency counter. Also thanks to the poster who showed us this site. It looks interesting. Such a rabbit hole.
About google books more generally, I recall when millions of books and old news sources were added to the database, all the oldest stuff was digitized by hand a couple decades ago. I knew someone who worked over in Ann Arbor, whose job was to help scan every book in the main University library there, page after page and book after book for Google (while wearing those special gloves that protect books from your acidic finger oils). I don’t know if I could have done that job. Separately, I miss my alma mater, Go Blue! I didn’t realize this ngram was around, but I know it’s using a very large database. I hope Google keeps it around for awhile.