Null Move

A null move is an empty move. It is illegal in an official chess game. 1.e4 White plays a common first move. 1...Ø Black plays a null move. 2.d4 White gets a pawn duo; he has a significant advantage.
Black to move.

Threat

A threat is a move that wins material or obtains a strategic advantage that one would play if his opponent were to play a null move.
White to move.
1.Rook-c1 White creates a threat. If black plays 1...Ø then white plays 2.Rook-captures-c8

Threat Position

A position where there is a threat is called a threat position no matter whose turn it is.
Black is creating a threat: 1...Queen-captures-g2#

Threat Execution

To execute a threat is to make a move that wins material or obtains a strategic advantage.
If it is black to move then he should play 1...Queen-captures-g2#

Simple Threat

A threat that needs one move to be carried out is a simple threat.
White to move.
1.h5 White creates a simple threat. 1...Ø 2.h-captures-g6

Complex Threat

A threat that needs more than one move to be carried out is a complex threat.
White to move.
1.Rook-dg1 White creates a complex threat. 1...Ø 2.Queen-g7 Bishop-captures-g7 3.h-captures-g7-check King-g8 4. Rook-h8-checkmate

Direct Threat

A direct threat is made by a piece that would carry out the threat or participate in carrying out the threat.
White to move.
1.Bishop-b3 White creates a simple, direct threat. 1...Ø 2.Bishop-captures-d5

Indirect Threat

An indirect threat is made by a piece that would not carry out the threat or participate in carrying out the threat.
White to move.
1.Bishop-c4-check White creates a complex, indirect threat. 1...King-h8 2.Knight-b5 Queen-b6 3.Knight-captures-d6

Trap

One can walk into a threat position; there, his opponent should realize a threat.
White to move.
White is threatening to win a pawn. 1...Ø 2.Knight-captures-d7 Rook-captures-d7 3.Rook-captures-c5 White has a material advantage.

In the game, black played 1...Queen-d6 which walks into a threat position. 2.Queen-h6-check King-captures-h6 3.Knight-captures-f7-check King-g7 4.Knight-captures-d6 White has a material advantage.

Zugzwang

Zugzwang is situation where one is forced to move into a threat position.
White to move.
1.e5 Ø 2.King-d7 King-f7 3.King-d6 White forces black to walk into a threat position. King-f8 4.King-captures-e6

Distant Threat

A future position where a threat is made is a distant threat.
White to move.
1.Queen-g4 Ø 2.f4 Ø 3.f5 White wins material. 3...Knight-d8 4.f6-check Qe6 6.Bishop-captures-e6-check

X-to-threat

X-to-threat is the number of moves needed to create a distant threat.
White to move.
White needs 3 moves to create his distant threat thus this position is 3-to-threat. 1.Queen-g4 Ø 2.f4 Ø 3.f5 White wins material. 3...Knight-d8 4.f6-check Qe6 6.Bishop-captures-e6-check

Ideal Threat

An ideal threat is the best distant threat.
White to move.
1.Knight-d2 Ø 2.Knight-f3 Ø 3.Knight-g5 White wins. 3...Ø 4.Queen-captures-h7-checkmate

Tactical Threat

A tactical threat is a move that wins material that one would play if his opponent were to play a null move.
White to move.
1.Bishop-f4 White creates a tactical threat. 1...Ø 2.Bishop-captures-d6 White has a material advantage.

Strategic Threat

A strategic threat is a move that obtains a strategic advantage that one would play if his opponent were to play a null move.
White to move.
1.Knight-g5 White creates a strategic threat. 1...Ø 2.Knight-captures-e6 White has the bishop pair in an open position.

Mixed Threat

A mixed threat is a move that wins material or obtains a strategic advantage that one would play if his opponent were to play a null move.
White to move.
1.h4 White creates a mixed threat. 1...Ø 2.h5 White wins material or 1...King-h8 2.Queen-g5 White wins the open d-file.

Positional Threat

A positional threat is a threat which improves one’s position.
White to move.
1.Rook-c1 Knight-captures-e5 2.Knight-captures-a7 White has improved his position: he has a queenside majority; he has gotten rid of the e5-pawn which was making his bishop bad; and he has isolated black's b-pawn.

Antipositional Threat

An antipositional threat is a threat which damages one’s position.
White to move.
1...Bishop-a4 Black creates an antipositional threat. 2.Knight-c3 Now black has to retreat the bishop as 2...Bishop-captures-c2 3.King-d2 traps the c2-Bishop.

Candidate Moves

When coming up with candidate moves, one should have checks, captures, and other types of forcing moves at the top of the candidates list. Forcing moves include threats and threats that can be carried out.
White to move.
Candidates
  1. h5
  2. f5
  3. Rook-e1
  4. Rook-h1
  5. King-f3
Forcing moves belong at the top of the list. 1.h5 creates a threat. Rook-f6 2.h-captures-g6 h-captures-g6 3.Rook-h1 King-f8 4.Rook-h7 White has a significant advantage: he has a mobile majority; he has a pig; and black's g6-pawn is isolated.