The smallest projective plane , aka the Fano plane, has seven points and seven lines. There are three point on every line and three lines through every point. Any two points are contained in exactly one line and any two lines have exactly one point in common. The triangular diagram is the most famous representation of the Fano plane with the seven small circles representing the points and the six line segments and the one large green circle representing the lines. Another fun mnemonic for the plane is to take the letters in THEY WAR as the points and the seven words in YEA WHY TRY HER RAW WET HAT as the lines.