"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 that has size of 10×16 to 10×24. 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: 5×12
• Tetris Brick: 6×9
• Tetris Worst 3: 15×14
• Tetrinsanity: 20½ h

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 20 hidden rows, where the tetrominoes are started in rows 21 and 22. (Tetris Worlds and Lockjaw are known to use a 24 height instead, but that was in 2002. This must have changed to 40 between 2002 and 2006.) Tetrominoes may land and lock partially within the "vanish zone"; they reappear once a line is cleared below them.

The tetris.comglossary 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 high.

In Tetris, Tetris Best, Tetris Best 2 (and mods) and Tetris Perfect (and mods), blocks in vanish zone are not stored, so they don't reappear. They are all based on Wes64's Tetris. Same with games similar to Brick Game.