This article explains how to use the Ngram Viewer tool in Google Books to conduct research and perform powerful searches.

An Ngram, also called N-gram, is a statistical analysis of text or speech content to find n (a number) of a given item in the text.

The search item can be anything, including phonemes, prefixes, phrases, and letters. Although an Ngram is unknown outside the research community, it is used in a variety of fields and has many implications for developers who code computer programs that understand and respond to natural spoken language.

In the case of the Google Books Ngram Viewer, the text to be analyzed comes from the large number of public domain books that Google has scanned to populate its Google Books search engine. For the Google Books Ngram Viewer, Google refers to the text you're about to search as the corpus. The Ngram Viewer aggregates by language, although you can analyze British and American English separately or merge them.