A sentence diagram is the result of a method by which someone indicates the various clauses, phrases, and parts of speech that make up a particular sentence. This can be done to varying degrees of complexity, and the difficulty of such diagrams often depends on how detailed the diagram is and the sentence that is used. At its most basic, such a diagram typically indicates what part of speech each word in the sentence belongs to. A more complicated sentence diagram is likely to document each clause included in a sentence, the different phrases that make up these clauses, and the parts of speech that create each phrase.
The process of creating a sentence diagram is typically taught in language classes, usually for the primary language of a particular speaker. More complex sentence diagramming is often done in college or university, usually in grammar and linguistics classes taken by students pursuing a degree in language. For some students, it may be seen as an arduous task that is as incomprehensible as it is seemingly endless. The purpose of creating a sentence diagram, however, is to demonstrate a full and flexible understanding of a particular language and how the various elements of that language are used to construct and express an idea.
Different types of notation can be used to create a sentence diagram, though these diagrams are usually made by first writing out a sentence. This is done with enough space around the sentence on the paper to create the diagram, which is usually created either above or below the sentence. There is no difference between diagrams created above a sentence and those created below; it typically depends on personal preference and how people are taught. Lines and brackets are often used in a sentence diagram to indicate which words belong together in the construction of a clause or phrase or to indicate what part of speech a word belongs to.
A simple sentence, such as “The cat jumped onto a table,” would have an equally simple sentence diagram. Since the sentence consists of only a single clause, it would not be necessary for a diagram to indicate clauses in the sentence. The sentence essentially consists of three elements, which are a subject, predicate, and a direct object. In this example, the subject is made up of a noun phrase, which consists of the article “The” and the noun “cat.”
The predicate of this sentence is a verb phrase, which consists simply of the verb “jumped,” and this would be indicated separately from the subject and direct object in a sentence diagram. This sentence only has a direct object, and no indirect object, which consists of a prepositional phrase. The prepositional phrase is itself made up of a preposition “onto” and a noun phrase, which consists of the article “a” and the noun “table.” The diagram would indicate each of the three elements of this sentence, as well as the separate phrases in each element, and then the parts of speech used to make up those phrases.