Understanding the difference between simple and complex sentences is fundamental to improving your writing style and clarity. A simple sentence contains a single, complete thought, while a complex sentence can express more intricate relationships between ideas.

The Building Blocks: Clauses

Before diving into sentence types, you need to understand clauses. A clause is a group of words with a subject and a verb.

• Independent Clause: Expresses a complete thought and can stand alone as a sentence. (e.g., The dog barked.)
• Dependent (or Subordinate) Clause: Has a subject and a verb, but does not express a complete thought and cannot stand alone. It often begins with a subordinating conjunction. (e.g., because the dog was hungry.)

Simple Sentences

A simple sentence consists of just one independent clause. It has a subject and a verb and expresses a single, complete thought. It can have compound subjects or verbs, but it still only has one main clause.

• The train arrived.
• Maria and Sam laughed and danced.
• The sun shines brightly in the summer.

Complex Sentences

A complex sentence is made up of one independent clause and one or more dependent clauses. The dependent clause is linked to the independent clause by a subordinating conjunction.

Independent Clause + Dependent Clause
// or
Dependent Clause, + Independent Clause

Common subordinating conjunctions include:

• after, although, as, because, before, if, since, unless, until, when, while

Punctuation Note

When the dependent clause comes before the independent clause, you must use a comma to separate them. If the independent clause comes first, no comma is needed.

• Although it was raining, we went to the park.
• We went to the park although it was raining.

Related Topics

• Sentence Fragments, Learn what happens when a clause can't stand alone.
• Passive Voice, Combine passive forms with complex sentence structures.
• Conditionals (If Clauses), A key type of complex sentence with dependent clauses.
• Varying Sentence Structure, Practical tips for mixing sentence types in your writing.