Pins

There are two types of pins, absolute and relative. An absolute pin is a tactic where a rook, bishop, or queen attacks an enemy piece that cannot move because it is in front of the king. A relative pin is the same except a higher value piece is behind the king. This allows the pinned piece to move however, will often lead to a loss in material.

Forks

A fork is a tactic where a piece attacks multiple pieces at the same time. This includes forks checking the king often leading to forcing the enemy to lose material.

Skewers

Similar to pins, a skewer is a tactic where a piece attacks a more valuable piece or king in front of a less valuable piece leading to losing material.

Discovered attack

A discovered attack is when moving one piece reveals an attack from another piece previously blocked. This is commonly found in the form of discovered checks when the second piece checks the king allowing the first piece to capture an enemy piece.

Removing a defender

Simply put, capturing an enemy piece previously defending another piece loosening the defense of the enemy player.

Zugzwang

A more complicated kind of tactic. Zugzwang is a term in chess describing a position where every one of the enemy player's possible moves worsens their position. If you're a beginner, don't worry about this too much for now.

Puzzles

Puzzles are highly recommended to strengthen tactics knowledge and understanding allowing them to be easier to recognise and play in an actual game. While chess.com requires higher memberships to play more puzzles daily, lichess is a free and extremely beneficial website that allows unlimited puzzles. A helpful checklist to identify tactics is to look at possible checks, captures, and attacks.