So we know that check means that the king is in danger and if it does not make it out alive from this danger, it will be checkmate and the game will be over.
Let’s take this example from the video. You should also know here that not all checks are good. Just because you see a check does not mean that it would be wise to play it, you need to consider the whole board’s situation.
In this game, we see that the white’s knight is already developed so it can be used to attack the black king. It can go to e5 and g5 but none of them would be helpful in attacking the black king, the knight is too far away which means that we can’t attack the king with the knight. The queen can also not attack because it will be blocked by a knight as it moves one step forward.
The bishop here might do the work for us. Both black king and the white bishop are in the light square. You must note that the dark-squared bishop cannot check the light squared king, it’s the wrong color, and hence we must only attack with the dark squared bishop.
As we move this bishop to b5, the king is now in danger. This brings the black king under attack and it is now checked.