1. The two independent clauses are closely related in meaning. The semicolon signals a stronger connection than a comma would.
Example: *The storm raged outside; the house creaked and groaned.*
2. The second clause elaborates on or explains the first clause.
Example: *The hikers were exhausted; they had been walking for hours in the blistering heat.*
3. The clauses are joined by a conjunctive adverb (e.g., however, therefore, moreover, nevertheless, etc.). The conjunctive adverb is preceded by a semicolon and followed by a comma.
Example: *The team had practiced hard; however, they lost the game.*
4. The clauses contain commas already. Using a semicolon avoids confusion and maintains clarity.
Example: *The dog, a golden retriever, barked loudly; the cat, a sleek Siamese, hissed in response.*
Important Note: Using a semicolon in place of a comma is incorrect if the two clauses are not independent or if they are not closely related in meaning.
For example, this is incorrect: *The dog barked; the cat hissed.* (These clauses are too simple and unrelated to warrant a semicolon.)