In the field of linguistics, a sentence is an expression in natural language, often defined to indicate a grammatical and lexical unit consisting of one or more words that represent distinct concepts. A sentence can include words grouped meaningfully to express a statement, question, exclamation, request or command.
As with all language expressions, sentences contain both semantic and logical elements (words, parts of speech), and also include action symbols that indicate sentence starts, stops, pauses, etc. In addition, sentences also contain properties distinct to natural language, such as characteristic intonation and timing patterns.
Sentences are generally characterized in most languages by the presence of a finite verb, e.g. “The quick brown fox jumps over the lazy dog”.
Components of a sentence
A clause consists of a subject and a predicate. The subject is typically a noun phrase, though other kinds of phrases (such as gerund phrases) work as well, and some languages allow subjects to be omitted. The predicate is a finite verb phrase: a finite verb together with zero or more objects, zero or more complements, and zero or more adverbials.
There are two types of clauses: independent and subordinate (dependent). An independent clause demonstrates a complete thought; it is a complete sentence: for example, “I am sad.” A subordinate clause is not a complete sentence: for example, “because I had to move.”
See also copula for the consequences of the verb to be on the theory of sentence structure.
A simple complete sentence consists of a single clause (subject and predicate). Other complete sentences consist of two or more clauses (see below).
One traditional scheme for classifying English sentences is by the number and types of finite clauses:
• A simple sentence consists of a single independent clause with no dependent clauses.
• A compound sentence consists of multiple independent clauses with no dependent clauses. These clauses are joined together using conjunctions, punctuation, or both.
• A complex sentence consists of at least one independent clause and one dependent clause.
• A complex-compound sentence (or compound-complex sentence) consists of multiple independent clauses, at least one of which has at least one dependent clause.
Sentences can also be classified based on their purpose:
• A declarative sentence or declaration, the most common type, commonly makes a statement: I am going home.
• An interrogative sentence or question is commonly used to request information — When are you going to work? — but sometimes not; see rhetorical question.
• An exclamatory sentence or exclamation is generally a more emphatic form of statement expressing emotion: What a wonderful day this is!
• An imperative sentence or command tells someone to do something: Go to work at
Major and minor sentences
A major sentence is a regular sentence; it has a subject and a predicate. For example: I have a ball. In this sentence one can change the persons: We have a ball. However, a minor sentence is an irregular type of sentence. It does not contain a finite verb. For example, “Mary!” “Yes.” “Coffee.” etc. Other examples of minor sentences are headings (e.g. the heading of this entry), stereotyped expressions (Hello!), emotional expressions (Wow!), proverbs, etc. This can also include nominal sentences like The more, the merrier. These do not contain verbs in order to intensify the meaning around the nouns and are normally found in poetry and catchphrases.
Sentences that comprise a single word are called word sentences, and the words themselves sentence words
A simple sentence, also called an independent clause, contains a subject and a verb, and it expresses a complete thought. In the following simple sentences, subjects are in yellow, and verbs are in green.
A. Some students like to study in the mornings.
B. Juan and Arturo play football every afternoon.
C. Alicia goes to the library and studies every day.
The three examples above are all simple sentences. Note that sentence B contains a compound subject, and sentence C contains a compound verb. Simple sentences, therefore, contain a subject and verb and express a complete thought, but they can also contain a compound subjects or verbs.
A compound sentence contains two independent clauses joined by a coordinator. The coordinators are as follows: for, and, nor, but, or, yet, so. (Helpful hint: The first letter of each of the coordinators spells FANBOYS.) Except for very short sentences, coordinators are always preceded by a comma. In the following compound sentences, subjects are in yellow, verbs are in green, and the coordinators and the commas that precede them are in red.
A. I tried to speak Spanish, and my friend tried to speak English.
B. Alejandro played football, so Maria went shopping.
C. Alejandro played football, for Maria went shopping.
The above three sentences are compound sentences. Each sentence contains two independent clauses, and they are joined by a coordinator with a comma preceding it. Note how the conscious use of coordinators can change the relationship between the clauses. Sentences B and C, for example, are identical except for the coordinators. In sentence B, which action occurred first? Obviously, “Alejandro played football” first, and as a consequence, “Maria went shopping. In sentence C, “Maria went shopping” first. In sentence C, “Alejandro played football” because, possibly, he didn’t have anything else to do, for or because “Maria went shopping.” How can the use of other coordinators change the relationship between the two clauses? What implications would the use of “yet” or “but” have on the meaning of the sentence?
A complex sentence has an independent clause joined by one or more dependent clauses. A complex sentence always has a subordinator such as because, since, after, although, or when or a relative pronoun such as that, who, or which. In the following complex sentences, subjects are in yellow, verbs are in green, and the subordinators and their commas (when required) are in red.
A. When he handed in his homework, he forgot to give the teacher the last page.
B. The teacher returned the homework after she noticed the error.
C. The students are studying because they have a test tomorrow.
D. After they finished studying, Juan and Maria went to the movies.
E. Juan and Maria went to the movies after they finished studying.
When a complex sentence begins with a subordinator such as sentences A and D, a comma is required at the end of the dependent clause. When the independent clause begins the sentence with subordinators in the middle as in sentences B, C, and E, no comma is required. If a comma is placed before the subordinators in sentences B, C, and E, it is wrong.
Note that sentences D and E are the same except sentence D begins with the dependent clause which is followed by a comma, and sentence E begins with the independent clause which contains no comma. The comma after the dependent clause in sentence D is required, and experienced listeners of English will often hear a slight pause there. In sentence E, however, there will be no pause when the independent clause begins the sentence.
COMPLEX SENTENCES / ADJECTIVE CLAUSES
Finally, sentences containing adjective clauses (or dependent clauses) are also complex because they contain an independent clause and a dependent clause. The subjects, verbs, and subordinators are marked the same as in the previous sentences, and in these sentences, the independent clauses are also underlined.
A. The woman who(m) my mom talked to sells cosmetics.
B. The book that Jonathan read is on the shelf.
C. The house which AbrahAM Lincoln was born in is still standing.
D. The town where I grew up is in the United States.
Adjective Clauses are studied in this site separately, but for now it is important to know that sentences containing adjective clauses are complex.
Rozakis, Laurie (2003). The Complete Idiot’s Guide to Grammar and Style pp. 167–168. Alpha
Jan Noordegraaf (2001). “J. M. Hoogvliet as a teacher and theoretician”. in Marcel Bax, C. Jan-Wouter Zwart, and A. J. van Essen. Reflections on Language and Language Learning. John Benjamins B.V.. pp. 24. ISBN 9027225842.