Safety of your king is an important factor in chess.
If your king isn't safe, you may lose the game due to a mating attack.
In this position the black king's shelter is severely weakened. The pawn in front of the king has disappeared. This means easy access to the king with your heavy pieces.
When you notice a bad king position like this, you should always search for an immediate win. The weakened king position has to be exploited as soon as possible (before it can be repaired).
In this case, you can make use of the bad king position through tactical means.
1.Qg4+, Kh8; 2.Qh4!,
and now the mating threat of Qxh7# can only be parried by f5, which gives the white queen the opportunity to capture the black queen.
When the king's shelter hasn't been weakened yet, it may be possible to break down the shelter by violent means.
In positions where you've aimed your pieces at the opponent's king, look for winning sacrifices....
The usual defender of h7 (the f6-knight) has been chased to a passive position.
Time has come to break down the remaining barriers.
1. Bxh7+, Kxh7; 2. Ng5+,
Var 1: 2...Kh6; 3.Ne6+, winning
Var 2: 2...Kg6; 3.h5+, Kf5; 4. g4+, Kf4; 5 Qf3#
Var 3: 2...Kg8; 3. Qh5, Bxg5; 4. hxg5, f6; 5. g6, with mate to follow.
In practice the break down of the king position may happen in many different forms.
Did I say king safety is very important? That's why castling is often done early in the game. This keeps the king safe.
Sometimes your opponent forgets about his kings safety. When you notice his unsafe king in the centre of the board, you should make him pay!
In this position, Black has left his king in the centre. He probably thought of king safety as a minor issue as related to winning three pawns.
He even gave up the possibility of castling into safety, as there is no safe place on either side of the board.
This wouldn't have to be a problem if there's no possibility of a mating attack.
Unfortunately..... White started an attack.
1.Rxe5!, dxe5; 2.Qxe5,
Variation 1: 2...Be7; 3. Bc6+, Kf8 (or 3...Qxc6, 4. Qxe6#); 4.Qxh8#.
Variation 2: 2...Qxe5; 3.Bc6+, Rxc6; 4. Rd8#.
Variation 3: 2...Kd7; 3. Qf5+, Ke8; 4.Bf7+, Qxf7; 5.Qxc8#.
Leaving your king in the middle longer than necessary may prove very dangerous and often destructive.
From now on, when thinking about chess strategy, take king safety into account!