Connections: Marking a connection production
Ticking This is a production database means that any run whose targets include this connectionstops and makes you type a word to agree before a single statement is sent.
Ticking This is a production database means that any run whose targets include this connection stops and makes you type a word to agree before a single statement is sent. §13 covers exactly what the prompt says and when it appears.
The Registered servers panel groups connections into Production and Other, so what is dangerous is visible without opening anything.