A Middlegame Lesson

Here are tactical themes and patterns that you should be familiar with :

Fork or double attack
Pins and skewers
Sacrifice
Discovered attack
Deflection (or distraction)
Double check
Counter-attack
Hanging (undefended) piece
Exposed king
In-between move
Trapped piece
Clearance – Opening a critical square, file or diagonal
Blocking – blocking a critical file or diagonal
Advanced pawn
Attraction
Zugzwang
X-ray attack
Weak back rank
Removing the defender
Overloading a defender
Simplification into a winning endgame
Indirect defense
Domination in chess