If you are new to tactics, you do not need 64 themes on day one. You need a small set of shapes that come up constantly. Learn these first and you will start winning material, and games, almost immediately.
The fork
A fork is one piece attacking two targets at once. Your opponent can only save one. The knight is the great forker because it attacks squares nothing can block.
e When the fork is a check, the opponent must deal with the king first, and you take the other piece for free. Always scan for a square where one of your pieces would hit two valuable things at once.
The pin
A pin freezes an enemy piece because a more valuable piece sits behind it on the same line. A pinned piece cannot do its job. It cannot defend or run. Once something is pinned, pile more attackers onto it.
g The skewer
A skewer is a pin in reverse: the valuable piece is in front, it is forced to move, and you capture the piece behind it. Skewers win rooks and queens in the endgame all the time.
d g Discovered attack & double check
A discovered attack happens when you move one piece and reveal an attack from another behind it: two threats from one move. Its deadliest form, the double check, forces the king to move no matter what.
e g The back-rank mate
The most common way beginner games end: a king trapped behind its own pawns, mated by a rook or queen on the first rank.
7 g Knowing this shape means you both deliver it and avoid it. A tiny move like …h6 early on gives your king an escape square and prevents disasters.
How to practise
Reading these is step one. They only stick once you have seen them hundreds of times. Drill each shape until you spot it on sight, then mix them so you learn to find the right one. That is what real games demand. Browse all the tactical patterns when you are ready for more, and train them on puzzles matched to your level.