Check: In order to put someone in check you must threaten your opponent’s
king. In order to escape check however you can do a number of things
you must capture the threatening piece, put one of your pieces in the treating
piece’s path, or move your king onto a non-threatened square.
Checkmate: In order to put a piece in checkmate you must not only put
your opponent’s piece in check but you must also threat all of the non-threatened
squares that his/her king could move on, and the king must not be able to
block the piece threatening him or capture the piece threatening him.
Stalemate: While in my experience this is a rare occurrence, a stalemate
happens when no moves can be made by a player but the said player is not
in checkwhen this has taken place the game is a draw.
When black’s turn game is stalemate