Ladder

A ladder is a situation in which both players move perpendicularly to an edge making a straight unbroken chain. The attacking player's chain is almost always further from the edge. Here is an example of the ladder starting from b4 and c3.

R4, C10, Vc1, Vc2, Hb2, Hd2, Hb4, Vc3, Hc4, Vd3, Hd4, Ve3, He4, Vf3, Hf4, Vj3

Red (vertical) to move. In this situation red has a sure win due to his ladder escape on j3. Of course he can start another ladder playing a4 but in that case, blue has a ladder escape on b2.