Punctuation · 20 June 2019
Colons are often used erroneously: The words preceding a colon must be a complete sentence like this one and the one before it—unless used for direct speech in quotations and dialogues. These sentences have at least one clause, a unit that can stand on its own—so if you were to isolate it, it would be complete. For example, ‘what you can find in this book is’ cannot stand on its own, so it is not a clause; the reader is waiting for more.