Word cloud or tag cloud (or weighted list in visual design) is a visual depiction of user-generated tags, or simply the word content of a site, used typically to describe the content of web sites. Tags are usually single words and are typically listed alphabetically, and the importance of a tag is shown with font size or color. Thus both finding a tag by alphabet and by popularity is possible. The tags are usually hyperlinks that lead to a collection of items that are associated with a tag.

Word cloud generator: Wordle.net.

The field of "culturomics" promises humanities researchers a robust quantitative tool to analyze cultural trends back to the 1500s.

An n-gram is a subsequence of n items from a given sequence. The items in question can be phonemes, syllables, letters, words or base pairs according to the application.

An n-gram of size 1 is referred to as a "unigram"; size 2 is a "bigram" (or, less commonly, a "digram"); size 3 is a "trigram"; and size 4 or more is simply called an "n-gram". Some language models built from n-grams are "(n − 1)-order Markov models".

An n-gram model is a type of probabilistic model for predicting the next item in such a sequence. n-gram models are used in various areas of statistical natural language processing and genetic sequence analysis. Source: Wikipedia, n-gram.