A sentence may consist of one clause (independent clause or dependent clause). An independent clause is also called the main clause. A dependent clause is also called a subordinate clause.
There are four kinds of sentence according to structure.
1. Simple Sentence
2. Compound Sentence
3. Complex Sentence
4. Complex-Compound Sentence
A simple sentence consists of only one independent clause containing a subject and a verb and it shows complete meaning. There is no dependent clause.
“An independent clause (also called the main clause) is called a simple sentence.”
She ate an apple.
They are working.
I bought a car.
A compound sentence consists of at least two independent clauses joined by coordinating conjunction. There is no dependent clause in a compound sentence. The coordinating conjunctions are used 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 the compound sentence.
I like an apple but my brother likes a banana.
I helped him and he got happy.
He lost two times yet he is not disappointed.
I asked him a question; he replied incorrectly.
She likes football but I don't like it.
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 a relative pronoun (that, who, which etc).
I saw the boy who had helped me.
She is wearing a shirt which looks awesome.
You can’t pass the test unless you prepare for it.
You can go out as long as Simon goes with you.
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 a dependent clause, a comma is used after the dependent clause in a complex sentence.
He is playing well although he is not fit.
Although he is ill, he is working 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.
1. He went to college and I went to a market where I bought a book.
2. I like Accounting but my bother likes Biology because he wants to be a doctor.
In the first of two sentences above, there are two independent clauses “he went to college” and “I went to a market”, and one dependent clause “where I bought a book”