This is a ready reference which is which one must understand but practice is imperative.
Chess Tempo
Fork: When a single piece make 2+ direct attacks at the same time. You can fork will all pieces.
Pin: When a piece is held in place and can't move without giving up a more valuable piece behind it. You can pin only with the Queen, Bishop and Rook
Absolute Pin: When a piece is pinned to the King, it cannot move as such move is illegal
Relative Pin: When a piece is pinned to to another piece of greater value, not the King. Moving the pinned piece is not illegal but it is not logical / it is a bad move
Trapping a Piece: This is when a material is attacked and has no safe squares or no moves to play
Skewker: It is an attack on 2 pieces that are lined up. First piece is of higher value and must move in response followed by capture of the less valuable piece behind it. You can Skewer only with the Queen, Bishop and Rook
Discovered Attacks: When one piece moves and uncovers an attack by another piece
A Discovered Double Attack is a variation where the moving piece also creates a different attack at the same time. This results in 2 pieces being attacked at the same time.
A Discovered Check is a variation where King is attacked by either of the piece while the other attacks another material. Defening the King becomes imperative allowing the capture of other attacked piece
A Discovered Double Check is a variation where 1+ piece attack the opponent King (Hidden piece and Moving piece). In this case, King must move to defend itself.
Wind-Mill: When Repeating Discovered Checks allows a piece to go on a rampage, capturing multiple pieces.
Sacrifices: This is when we give up a material of higher importance to gain a dynamic positional advantage
Queen Sacrifice: This is when we allow the Capture of Queen to have a better position, justified compensation in material or determing win
Exchange Sacrifice: This is when we give up a material of higher importance for relative minor piece
Clearance Sacrifice: This sacrifice clears the space. When we have a position where a potential attack is blocked by one of our own pieces and we intend to clear it to follow through the potential attack
Creating Forcing Moves: It is a sequence where you control the game by directly determining the moves for the opponent. This has different intentions. In an otherwise loosing game, forcing for a Draw by stopping winning chances of opponent is intended. This is achieved by the following
Forcing a Stalemate or a Draw: When you repeat the moves or lock your pieces
Perpetual Checks: When you can continuously check the opponent but cannot checkmate
Interference: This occurs when the line the line between and attacked piece and its defender is interrupted by interposing piece.
Overloading Advantage: When you take the advantage of the opponents one piece which is assigned to protect multiple pieces, squares or threats at the same time
Deflection: The idea is to chase the opponent away from an important square in the position. Often used to deflect a defender of opponent to attack a defended piece
Decoy: This idea is to bring opponent to a Poison Square usually with a forced move. (The Poison Square is where opponent has a major threat)
X-Ray: It is an indirect attack on an enemy piece or indirect defense through an enemy piece
Zugzwang: It means you create such a position for your opponent where, all their moves are bad moves. We usually play a waiting move to create this.
Zwischenzug: (also known as In Between Move) When a player inserts a unexpected move in between an otherwise spequence of force moves
Undermining: It involves attacking to deflect or capture a critical defending piece to gain a significant advantage in material or position.
Under-promotion: It means, we promote a pawn to a small ranking material, other than Queen to achieve either a threat neutralization, better position or desired result - checkmate or draw
Exposing Hanging Pieces: This is when we create a position where 1+ undefended opponent pieces are simultaneously attacked. This ensures that atleast one can be captured
Support Mate: When you checkmate with a piece which is supported by other piece
Smothered mate: When Kight checkmates opponent which is surrounded by its own pieces
Back Rank Mate: When opponent King gets checkmated from the only available degree of freedom