[html] Why do symbols like apostrophes and hyphens get replaced with black diamonds on my website?

You need to change your text to 'Plain text' before pasting into the HTML document. This looks like an error I've had before by pasting straight from MS word.

MS word and other rich text editors often place hidden or invalid chars into your code. Try using — for your dashes, or ’ for apostrophes (etc), to eliminate the need for relying on your char encoding.