The four types of sentence structures are simple, compound, complex, and compound-complex. The quantity and arrangement of clauses determines the makeup of each type of sentence structure. A clause is a grouping of words with both a subject and a verb that can (but doesn’t always) form a sentence. If the clause can form a complete thought on its own, it’s considered an independent clause. If the clause depends on another part of the sentence to complete the thought it expresses, it’s called a dependent clause. For example, “when he got home from school” is a dependent clause. It isn’t a complete thought even though it contains a subject and a verb.
In a simple sentence, there’s only one independent clause. “I like coffee” and “Dave works at the library” are both examples of simple sentences. They each contain one subject (I and Dave) and one verb (like and works).
A compound sentence contains two independent clauses linked by a conjunction. “The dog ran around in the backyard, and now he’s taking a nap” is a compound sentence. Both of the clauses are complete thoughts, and could stand alone if the conjunction (and) was removed.
A complex sentence links one independent clause with at least one dependent clause. A common example of this type of structure is the if/then sentence. For example, “If I won the lottery, then I would buy a new car” is a complex sentence. If I won the lottery is a dependent clause that can’t stand alone because it’s not a complete thought. When you add a comma and the independent clause then I would buy a new car, it becomes complex.
In a compound-complex sentence, there’s more than one independent clause and at least one dependent clause. For example, “Randy is in a band, but he’s the singer because he can’t play an instrument.” This is a compound-complex sentence. It contains two independent clauses (Randy is in a band and he’s the singer) and one dependent clause (because he can’t play an instrument).
Putting It All Together
You can create the four types of structures by changing or adding additional clauses:
- “I broke my arm.” (Simple sentence)
- “I fell off my bike, and I broke my arm.” (Compound sentence)
- “When I fell off my bike, I broke my arm.” (Complex sentence)
- “When I fell off my bike, I went to the hospital because I broke my arm.” (Compound-complex sentence)
Different sentence structures are determined by the number of independent and dependent clauses. One independent clause is a simple sentence. Two independent clauses is a compound sentence. One independent clause and at least one dependent clause make a complex sentence. A compound-complex sentence is made up of two or more independent clauses and at least one dependent clause.