The letter OK is the sign of objection killed or approval. This OK Button symbol enclosed in a square is opposite of the Squared NG emoji.
NOTE: The Unicode 6.0 of this emoji was approved in 2010 under the name “Squared OK” added to emoji 1.0 in 2015.
🆗 OK Sign
🆗 Squared OK
:ok: (Github, Slack)emoji copy and pasteok emoji