The copyright sign.
More from Tech Symbols.
The quickest way is to copy © from this page and paste it anywhere. You can also insert it with its Unicode, HTML, or alt code listed above.
© is U+00A9 (decimal 169).
Use © in HTML to render © on a web page.
On Windows you can type it with Alt+169 (hold Alt and enter the number on the numeric keypad).
Yes — copying is completely free and unlimited, and works right in your browser with no sign-up.