Sentences in English come in four basic structures. Understanding them helps you write with variety and clarity.
A clause is a group of words with a subject and a verb. An independent clause can stand alone as a sentence. A dependent clause cannot.
1. Simple Sentence
One independent clause — one subject and one verb (or compound subject/verb).
The cat slept. John and Maria left early. She woke up, ate breakfast, and left for work.
Simple sentences are clear and direct. Use them for impact.
2. Compound Sentence
Two or more independent clauses joined by a coordinating conjunction (FANBOYS) or a semicolon.
I wanted to go, but I was too tired. She studied hard, so she passed the exam. The sun set; the stars appeared.
Form: Independent clause + , + conjunction + independent clause
3. Complex Sentence
One independent clause + one or more dependent clauses joined by a subordinating conjunction (because, although, when, if, etc.).
Because it was raining, we stayed inside. I called him when I arrived. She passed the exam although she didn't study much.
If the dependent clause comes first, use a comma. If it comes after the independent clause, no comma is needed.
4. Compound-Complex Sentence
Two or more independent clauses + one or more dependent clauses.
When I arrived (dependent), I called her (independent), but she didn't answer (independent). Although she was tired (dependent), she finished her work (independent), and she went home (independent).
Comparison Table
| Type | Independent Clauses | Dependent Clauses | Example | | ---------------- | ------------------- | ----------------- | ----------------------------------------------------------------------------------------------------- | | Simple | 1 | 0 | I like coffee. | | Compound | 2 | 0 | I like coffee, but she prefers tea. | | Complex | 1 | 1 | Although I like coffee, I drink tea at night. | | Compound-Complex | 2 | 1 | Because I was tired (dep), I went to bed early (ind), but I couldn't sleep (ind). |
Common Mistakes
- Comma splice: joining two independent clauses with only a comma: ~~I went home, I was tired.~~ → I went home because I was tired. or _I went home ; I was tired. _
- Sentence fragment: a dependent clause without an independent clause: ~~Because I was tired.~~ → I went to bed because I was tired.
- Run-on sentence: joining independent clauses without any punctuation: ~~I went home I was tired.~~ → I went home because I was tired.