What do you understand by the 'bitcoin alert key'

[Xtynehappy]

Search engine results read to me that it's basically something that the miners rely on. It's part of the protocol that can broadcast a message to all concerned, in a way that the miner know 100% it's from an "authorized" source.

 

[Suba]

The alert key or alert system is a mass notification mechanism on the Bitcoin network, this notification is sent massively to all nodes. The alert key is especially intended if there is a Bitcoin core update, so that all clients/nodes immediately change their software. The first time the alert key was launched was in Bitcoin core version 0.3.