Connect Four (also known as Captain’s Mistress, Four Up, Plot Four, Find Four, Four in a Row, Four in a Line, Drop Four, and Gravitrips (in Soviet Union)) is a two-player connection game in which the players first choose a color and then take turns dropping one colored disc from the top into a seven-column, six-row vertically suspended grid. The pieces fall straight down, occupying the lowest available space within the column. The objective of the game is to be the first to form a horizontal, vertical, or diagonal line of four of one’s own discs. Connect Four is a solved game. The first player can always win by playing the right moves.

The game was first sold under the Connect Four trademark by Milton Bradley in February 1974.

Tic-tac-toe Collection implements a game with the same rules using the name Drop Four. As is standard, the size of the board can be changed and all other game options still exist.