Compound Sentence

A compound sentence has two independent clauses or sentences. The independent clauses can be joined by a coordinating conjunction (such as "and," "for" and "but") or a semicolon.

Definition of compound sentence

Compound sentences are one of the four main types of sentences found in the English language. They are defined as complete sentences that have at least two independent clauses. 

It is important to know that an independent clause expresses a complete thought or sentence and can stand alone. For example, “He slept.” is a complete sentence that has both a subject and a verb. 

Dependent clauses are a little different because they are considered incomplete sentences and cannot stand alone. This is because dependent clauses do not have both a subject and a verb. 

The phrase “once upon a time” is not a complete sentence because it has neither a subject nor verb. “Once upon a time” is a prepositional phrase.

Compound sentences and their clauses

The two independent clauses (found in a compound sentence) are typically connected with a conjunction or a comma, a semicolon (;) or a colon (:). Compound sentences rarely feature a colon since the colon (:) rarely links an independent clause.

Other compound sentences are connected using a dash (-) or a conjunction with a semicolon (;). Both are very rare because the grammatical rules involved are more advanced than what is found in common writing and speech. 

Below are examples of compound sentences in which the independent clauses are underlined. The conjunctions are not underlined.

• Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. 
• There used to be a real me, but I had it surgically removed. 
• Go, and never darken my towels again. 
• Any fool can criticize, condemn, and complain - and most fools do. 

Types of sentences in American English 

Compound sentences are one of the four main sentence structures found in American Standard English and other forms of English. The four types of sentences include simple sentences, complex sentences, compound sentences, and compound-complex sentences.

The most common type of sentence is the simple sentence. This is because it requires less information, is shorter, and may be easier to understand. Compound sentences are the next most common sentence structure because the rules are a little more simplistic than complex and compound-complex sentences. 

Examples of the four types of sentences

Simple Sentence features one independent clause that stands alone, as shown below:

“Curiosity killed the cat.”

Complex Sentences are comprised of an independent clause and at least one dependent clause, as show below:

“The human brain never stops working until you stand up to speak in public.”

Compound Sentences have at least two independent clauses. In this example, the independent clauses are separated by a comma.

“I always wanted to be somebody, but I should have been more specific.”

Compound-Complex Sentences have more elements than those described above. These sentences have at least two independent clauses and at least one dependent clause.

“I stopped believing in Santa Claus when my mother took me to see him in a department store, and he asked for my autograph.”