The Greek Lunate Sigma Symbol symbol (ϲ). Copy and paste it, or use its Unicode, HTML, and CSS codes.
More from Greek Letters.
The quickest way is to copy ϲ from this page and paste it anywhere. You can also insert it with its Unicode, HTML, or alt code listed above.
ϲ is U+03F2 (decimal 1010).
Use ϲ in HTML to render ϲ on a web page.
On Windows you can type it with Alt+1010 (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.