--

--, a string of two hyphen-minus characters or - -, may approximate or refer to:

• En dash (–)
• Em dash (—), as a typewriter approximation
• Sig dashes (--), the email and Usenet signature delimiter
• For Unix commands, used as a prefix for command options. By itself, it typically means the end of command options.
• Decrement operator in some programming languages
• Inline comments, commonly used in programming languages
• Emoticon, a pictorial representation of a facial expression in characters

Look up --, ---, ----, or —— in Wiktionary, the free dictionary.