The second line refers to all points that lie on the second line, starting from each of the four sides towards the centre.
The second line is normally used in conjunction with plays on the third line and fourth line.
In the endgame, the biggest moves are often found on the second line between opposing groups.
- Making repeated plays along the second line is called crawling.
- crawling on the second line produces only a single point of territory for each stone spent, and is thus very inefficient. For this reason, the second line is called the line of defeat.
- An extension from a third-line stone along the second line is called a slide.
- Plays made directly on the second line without immediate support from other stones are called submarines.
- Jumps down from the fourth to the second line balance between fast and thin. See for instance the footsweep.
There are a number of tesuji particular to the second line. They often take advantage of the potential for shortage of liberties involved in plays on the second line.
- The underneath attachment
- Hitting under
- Certain clamps, eg. the endgame clamp