Theory:

Tetromino
A geometric shape composed of four squares, which are connected orthogonally is called a Tetromino.
  • The name "Tetromino" is a combination of the prefix tetra - "four" (from Ancient Greek), and "domino" ( a traditional tile-based game from China).
  • To further understand tetromino, it is essential to know about Domino & Trinomino.
  
Domino:
  • Two unit squares of each \(1\)\(cm\) are joined together (edge to edge) to form a Domino.
vertical & horizontal domino.png
 
Trinomino:
  • Similarly, Three unit squares of each \(1\)\(cm\) are joined together (edge to edge) to form a Trinomino.
  • The word “Tri” means three. Hence, joining three squares is called "Trinomino".
vertical & horizontal trinomino.png
Important!
But unlike Domino, Trinomino can also be arranged into four other different ways.
They are as follows:
types of trinomino.png