### 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.

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".
Important!
But unlike Domino, Trinomino can also be arranged into four other different ways.
They are as follows: