A sentence is a group of words that contains a subject (at least an understood subject) and a verb and expresses a complete thought. Moreover, all sentences are made up of clauses.
What is a clause? Well, a clause is a group of words containing a subject and verb that are working together, along with any necessary modifiers. For example,
My mother baked a chocolate cake.
“Mother” is the subject; “baked” is the verb; “my” is a possessive pronoun, telling us whose mother; “a” is an article, which is a special adjective; “chocolate” is an adjective, telling us what kind of cake; and “cake” is the direct object of the verb “baked.”
Also bear in mind that there are independent clauses and dependent (or subordinate) clauses; and, as the word “independent” implies, an independent clause can stand by itself because it expresses a complete thought; however, a dependent clause, as the word “dependent” implies, cannot stand by itself since it depends upon another clause (an independent clause) to provide it with full meaning.
Now, regarding sentences, one must realize there are simple sentences, compound sentences, and complex sentences.
A simple sentence contains only one independent clause and no dependent clauses.
Of course, simple sentences can contain compound subjects and/or verbs:
- John and Mary are getting married this Saturday. (Compound subject—John and Mary)
- John went to the store and bought a six-pack of beer. (Compound verb—went and bought)
- John and Mary got married on Saturday and divorced on Monday. (Compound subject—John and Mary; compound verb—married and divorced)
Unlike simple sentences, however, compound sentences contain two or more independent clauses usually linked together by one of the seven coordinating conjunctions (for, and, nor, but, or, yet, and so), or a conjunctive adverb such as “then, next, also, moreover, however, furthermore, consequently, thus, nevertheless, on the other hand, for example,” and “for instance.”
- John and Mary met in an Internet Chat-Room, and they immediately fell head-over-heels in love.
- John took one look at Mary’s photo and swooned, for he instantly recognized his long awaited soul mate.
- Mary watched the video of John dancing; however, she fell in love with him anyway.
And that brings us to complex sentences, which are sentences that consist of at least one independent clause and one or more dependent clauses.
- John, who lives in Maine, is my older brother; however, he acts much younger because he is very immature for his age.
In the sentence above, “John is my older brother” and “He acts much younger” are both independent clauses, and the two underlined clauses are dependent clauses.
- Mary, who graduated with honors and has a seven-year plan for success, is John’s total opposite and extremely mature for her age.
In this sentence, “Mary is John’s total opposite and extremely mature for he age” is the independent clause, and the underlined clause is dependent upon it.