Kinds of Sentences According to Structure

A sentence may consist of one clause (independent clause) or more clauses (independent and dependent clauses). An independent clause is also called main clause. A dependent clause is also called subordinate clause.

On the basis of numbers of clause and types of clauses present in a sentence, sentences are divided in to four kinds.

Simple Sentence

      A simple sentence consists of only one independent clause containing a subject and a verb and it expresses complete thought. There is no dependent clause.
“An independent clause (also called main clause) is called a simple sentence.”

Examples.
             He laughed.
             She ate an apple.
             They are sleeping.
             I bought a book.

Compound Sentence

A compound sentence consists of at least two independent clauses joined by coordinating conjunctions. There is no dependent clause in compound sentence. The coordinating conjunctions use to join independent clauses are “for, and, nor, but, or, yet, so”. Independent clauses can also be joined by a semicolon (;). A comma may or may not be used before the conjunction in compound sentence.

Examples
            I like an apple but my brother likes a mango.
            I helped him and he became happy.
            He failed two times yet he is not disappointed.
            I asked him a question; he replied correctly.

Complex Sentence

A complex sentence consists of one independent clause and at least one dependent clause joined by subordinating conjunction (because, although, since, when, unless etc) or relative pronoun (that, who, which etc).

Examples
            I met the boy who had helped me.
            She is wearing a shirt which looks nice.
            You can’t pass the test unless you study for it.
If a complex sentence begins with an independent clause, a comma is not used between clauses in a complex sentence. If a complex sentence begins with dependent clause then a comma is use after dependent clause in a complex sentence. See the following example.

           He is playing well although he is ill.
           Although he is ill, he is playing well.

Complex - Compound Sentence   

A complex-compound sentence consists of at least two independents and one or more dependent clauses. It is also sometimes called compound-complex Sentence.

Examples
      1. He went to college and I went to a market where I bought a book.
      2. I like Mathematics but my bother likes Biology
            because he wants to be a doctor.
In the first sentence of above sentence, there are two independent clauses “he went to college” and “I went to a market”, and one dependent clause “where I bought a book”.