Cheat Sheet of Parameters That Can Be Set for the Ngram Viewer

(excerpted and quoted with adaptation from About Google Ngram Viewer)

• Wildcard search ("search phrase*")
  
• When you put a * in place of a word, the Ngram Viewer will display the top ten substitutions. For instance, to find the most popular words following "University of", search for "University of *".
• Inflection search ("search phrase_INF")
• An inflection is the modification of a word to represent various grammatical categories such as aspect, case, gender, mood, number, person, tense and voice. You can search for them by appending _INF to an ngram. For instance, searching "book_INF a hotel" will display results for "book", "booked", "books", and "booking":
• Part-of-speech Tags
• ("searchword_Verb")
• ("searchword_Noun")
• ("searchword_ADJ")  adjective
• ("searchword_ADV")  adverb
• ("searchword_PRON)  pronoun
• ("searchword_DET)  determiner or article
• ("searchword_ADP)  an adposition: either a preposition or a postposition
• ("searchword_NUM)  numeral
• ("searchword_CONJ)  conjunction
• ("searchword_PRT)  particle
• ("searchword_ROOT)  root of the parse tree     These tags must stand alone (e.g., _START_)
• Example: Consider the word tackle, which can be a verb ("tackle the problem") or a noun ("fishing tackle"). You can distinguish between these different forms by appending _VERB or _NOUN: , etc.
• Most frequent part-of-speech tags for a word can be retrieved with the wildcard functionality.  For example: query cook_*:
• Stand-alone usage of Part-of-speech tags (above tag used in the format "_tags_")
• For example, you can use the DET tag to search for "read a book," "read the book", "read that book," "read this book," and so on
• Start and End of Sentences ("_START_") ("_END_")  
• The Ngram Viewer tags sentence boundaries, allowing you to identify ngrams at starts and ends of sentences with the START and END tags, for example: "_START_ President Lincoln")
• Dependency Relations ("mainword=>dependentword")
• Sometimes it helps to think about words in terms of dependencies rather than patterns. Let's say you want to know how often tasty modifies dessert. That is, you want to tally mentions of tasty frozen dessert, crunchy, tasty dessert, tasty yet expensive dessert, and all the other instances in which the word tasty is applied to dessert. For that, the Ngram Viewer provides dependency relations with the => operator:\.
• Root Word in Sentence ("_ROOT_=>searchword")
• Every parsed sentence has a _ROOT_. Unlike other tags, _ROOT_ doesn't stand for a particular word or position in the sentence. It's the root of the parse tree constructed by analyzing the syntax; you can think of it as a placeholder for what the main verb of the sentence is modifying. So here's how to identify how often will was the main verb of a sentence: "_ROOT_=>will".  This will return results in which "will" is part of the sentence Larry will decide. but not Larry said that he will decide, since will isn't the main verb of the latter sentence.
• Ngram Compositions
• The Ngram Viewer provides five operators that you can use to combine ngrams: +, -, /, *, and :.

• Searching inside Google Books
• Below the graph, we show "interesting" year ranges for your query terms. Clicking on those will submit your query directly to Google Books. Note that the Ngram Viewer is case-sensitive, but Google Books search results are not.
• Corpus Selection ["(searchworld:eng_2012)", "(searchword:fre_2012)", etc.]
• The : corpus selection operator lets you compare ngrams in different languages, or American versus British English (or fiction), or between the 2009 and 2012 versions of our book scans. Here's chat in English versus the same unigram in French: (chat:eng_2012) versys (chat:fre_2012)
• Corpora: Below are descriptions of the corpora that can be searched with the Google Books Ngram Viewer. All corpora were generated in either July 2009 or July 2012; we will update these corpora as our book scanning continues, and the updated versions will have distinct persistent identifiers. Books with low OCR quality and serials were excluded.