 Corpora can be annotated in ways that permit certain kinds of analysis and grammar testing. One basic kind of annotation is part-of-speech tagging, in which each word is labeled with its syntactic category. Another is lemmatization, which classifies the different morphologically inflected forms of a word as belonging together (goes, gone, going, and went belong with go, for example). A more thoroughgoing kind of annotation involves adding markup that encodes trees representing their structure; an example like That road leads to the freeway might be marked up as a Clause within which the first two words make up a Noun Phrase (NP), the last four constitute a Verb Phrase (VP), and so on, giving a structural analysis represented thus: