Box Size
  
Almost like a Tic Tac Toe game, a box size comes into play when an investor is using a point and figure chart to keep track of rising and falling stock prices.
An X means the price is rising and (take a guess here) an O indicates the price is falling. Since you may not want to enter Xs and Os every time the prices changes by a minute amount, you would set a box size. This would be the minimum amount the price would have to change before you enter the X or O.
You might set the box size at $1.00, so a new X or O would be printed every time the price moves at least that amount. Xs are stacked up on each other as the price continues to rise, and when they fall, the Os are stacked downward to the right of the Xs.
The smaller the box size, the more details you'll see on stock price changes.
And, uh...that's it. xoxo