Em dash (—, shift + option + dash on Mac; Alt + 0151 on Windows) acts as a break in a sentence, similar to, but stronger than a comma. No spaces before or after the em dash. Use an em dash on both sides of the full thought. Think “m” is bigger than “n” or “m” is for a “memory.” (e.g. Man Searched for Meaning—the greatest book in the world—states that…)