A simple sentence consists of just one clause. As the name itself indicates, it is the simplest type of sentences.

A compound sentence has at least two main clauses. It doesn’t have a subordinate clause. Note that the clauses in a compound sentence are connected by a coordinating conjunction.

A simple sentence can be converted into a compound sentence by expanding a word or a phrase into a clause.

Study the example given below.

She must come in time to avoid punishment.

The above sentence is a simple sentence because it has just one clause. The number of clauses in a sentence is equal to the number of finite verbs in it. Note that infinitives, gerunds and participles are non-finite verbs and as such they cannot form clauses.

We have already seen that the example sentence given above is a simple sentence. It can be converted into a compound sentence by expanding the infinitive phrase ‘to avoid punishment’ into a clause.

She must come in time or she will be punished.

More examples are given below.

Having taken his meals he threw away the crumbs to the sparrows. (Simple sentence)

He took his meals and threw away the crumbs to the sparrows. (Compound sentence)

Besides looting the shop, the robbers set it on fire. (Simple sentence)

The robbers not only looted the shop, but also set it on fire. (Compound sentence)

In spite of working hard, he failed. (Simple sentence)

She worked hard, still she failed. (Compound sentence)

Notes

By using a subordinating conjunction instead of a coordinating conjunction, we can make complex sentences.

The last two sentences, for example, can be rewritten as:

After they looted the shop, the robbers set it on fire. (This is a complex sentence because the two clauses are connected using the subordinating conjunction after.)

Though she worked hard, she failed.