A comma follows "therefore" when it introduces a new independent clause. This rule applies because "therefore" acts as a coordinating conjunction in such cases.
When "therefore" connects two complete thoughts, place a comma before it. This pause signals the shift from one idea to another. For example:
We studied hard; therefore, we passed the exam.
Without the comma, the sentence would lack clarity and proper flow.
The comma rule for "therefore" falls under the broader category of comma usage with transitional phrases. Other similar transitions include "however," "nevertheless," and "consequently."
Many writers confuse "therefore" with "thus" or "hence," which sometimes don't require commas. For instance:
She finished her work thus received praise.
This sentence is correct without a comma because "thus" functions differently. However, "therefore" always needs a comma when introducing a new clause.
British English often omits the comma after "therefore," unlike American English. For example, a British writer might write:
He was tired therefore he went to bed.
This difference highlights regional variations in punctuation rules.
Consider this sentence without a comma:
The project failed therefore the team was disappointed.
Adding the comma improves readability:
The project failed, therefore, the team was disappointed.
This change makes the relationship between the two clauses clearer.