What is a double check in chess?

Chess tactic - Wikipedia

Double Check Mate Examples

Double check stock image. Image of white, cells, international

Triple Double-Check ( The Power of Double-Check ep.2 )

I moved my bishop from C4 to D5, getting a double check and

Double Check achievement in Chess Ultra

25 Chess Tactics All Players Must Know - TheChessWorld

So satisfying, the power of a double check. : r/chessbeginners

The game Reti vs. Tartakower 1910 has one of the most powerful double checks ever! Have you ever used a double check to win a game of chess?, By ChessKid.com

In order to win you should always double check chess design Photographic Print by tobistees