What does 'mate in one' mean in chess? Apparently, I've done it

White to move, is this a draw? Or a forced mate : r/chessbeginners

Checkmate - Wikipedia

I was randomly playing against chess.com's top level bot and it made this blunder. No clue how. (Game link is in comments) : r/chessbeginners

My Opponent resigned, Can someone explain to me why this wasn't a checkmate : r/chessbeginners

DRAW - Why?? - Chess Forums

Mate in 5 I saw while watching a game between GMs (the GM didn't see, game in the first comment) : r/chess

Why does Stockfish sometimes promote a pawn to a rook instead of a queen? - Quora

What does 'mate in one' mean in chess? Apparently, I've done it many times since my buddy keeps telling me it's my favorite checkmate move? - Quora

In this position, black to move resigned. Easy puzzle: why did he resign? Hard puzzle: what winning move could he have played instead of resigning? : r/chess

WHITE to move and MATE IN 3 : r/chess

Opening Questions And A Dream Mate

Bad puzzles or tactic solutions - Chess Forums

Tales from the jar side: Dealing with failure, Never postpone a progress meeting, and Shameless pandering to my awesome readers