What does the Ngram Viewer do? When you enter phrases into the Google Books Ngram Viewer, it displays a graph showing how those phrases have occurred in a corpus of books (e.g., "British English", "English Fiction", "French") over the selected years. Let's look at a sample graph: This shows trends in three ngrams from 1960 to 2015: "nursery school" (a 2-gram or bigram), "kindergarten" (a 1-gram or