What it is
It's the trade opened to win back a loss, not because there's a setup. It usually comes a few minutes after the stop, with a bigger size and fewer checks: that's why a bad day turns into a disastrous one.
The signs
You re-enter the same instrument right after a stop, raise the size to recover quickly, skip the checklist, trade outside your hours. If your journal shows trades bunched together after a loss with a worse R than average, that's revenge trading.
The protocol to stop it
After every stop, a mandatory 15-minute break away from the screen. After two losses on the same day, the day is over. Never raise your size on a day with a loss.
Write these rules into your method and let the journal block new entries when you exceed them: you made the decision with a cool head, not at the worst moment.