Tetromino

A tetromino, sometimes called tetramino or tetrimino, is a four-squared polyomino. The seven tetrominoes are i, o, t, s, z, j, and l.

i
Other names include straight, stick, and long.

o
Other names include square and block.

s
Other names include inverse skew.

z
Other names include skew.

j
Other names include gamma or inverse l.