Lesson terms
Lessons use everyday words. We always say disc, never stone. Older writeups sometimes use the extra names in gray — you do not need them to play.
- Disc
- The piece you drop. Lessons say disc — not stone or checker.
- Drop
- Place a disc in a column. Gravity pulls it to the lowest empty square.
- Landing square
- The empty square a disc will occupy if you play that column now.
- Four-line
- Four squares in a row — across, stacked, or on a slant — that would win if they all hold your discs.
- Winning squarealso called out, threat cell
- An empty square on a four-line. If the next disc can land there, it is a win this turn.
- Later winning square
- A winning square that still needs a disc under it before anyone can land there.
- Who lands there
- Count the empty squares from the winning square down to the landing square. Odd count: the player to move lands there. Even count: the other player does.
- Block
- Drop on their landing square so they cannot complete four on their next turn.
- Double threat
- One drop that creates two winning squares for your next turn. They can stop only one.
- Fork
- One drop that aims at two fours later — not two wins next turn.
- Odd and even rows
- Count from the bottom. First player usually owns rows 1, 3, 5. Second player owns 2, 4, 6.
- Even-row finish
- Gold wants the empty finishing square on row 2, 4, or 6 — taken when it is the landing square, not filled just to fill it.
- Dead threat
- A three whose finishing square they will land on. Do not keep building that line.
- Forcing dropalso called sente
- A drop that makes a winning square for next turn. They must answer it or you win.
- Quiet dropalso called gote
- A drop they can ignore. It does not create a must-block.