"PLAYFIELD: This is where the action is."
—Manual for Tetris for NES

The playfield is the grid into which tetrominoes fall, also called the "well" (common in older games) or the "matrix" (especially in more recent Tetris brand games). The playfield is surrounded by a frame called the tetrion, which controls the overall behavior of tetrominoes.

The vast majority of tetromino based games use a playfield 10 cells wide and between 16 and 24 cells tall. Notable exceptions are the following:

• Abandoned Bricks: 9 w
• Gnometris: 11 w until mid-2007; then 14 w
• Tetrinet: 12 w
• Tetris Jr.: 8 w
• Tetris Wristwatch: 6 w
• Tetripz: 11 w
• TAP Doubles Mode: 14 w
• Tetris (NES, Tengen) Cooperative Mode: 14 w
• Tetris Party Doubles: 20 w
• Tetris Party Beginner's Tetris: 5 w and 12 t

Columns are conventionally numbered from left to right, and rows from bottom to top.

Vanish zone

Placing blocks in the vanish zone and then revealing them by clearing lines.

The Tetris Guideline specifies a playfield 10 blocks wide by at least 22 blocks tall, where the tetrominoes are started in rows 21 and 22. (Tetris Worlds and Lockjaw are known to use a 24-row playfield.) Most games hide rows 21 and up. Tetrominoes may land and lock partially within the "vanish zone"; they reappear once a line is cleared below them.

The tetris.com glossary calls the vanish zone as the Buffer Zone and defines its dimensions as the same as those of the Matrix (visible portion of the playfield), meaning the playfield is 10 blocks wide and 40 blocks tall.