Shicho is the Japanese term for a method of capture in the board game go. The English term is ladder.
Shicho is one of the two fundamental methods of capture in go, the other being geta (net in English).
..........
..........
..........
..O.......
.OX.......
..OO......
..........
Note the black stone (X) has only one liberty. Though it hadn't been captured yet, it is good as dead, because it is caught in the shicho, or ladder. If black tries to escape...
.......... ..........
.......... ..........
.......... ..........
..O....... ..O.......
.OXX...... .OXXO..... <--- white responds by again putting
..OO...... ..OO...... black in atari.
.......... ..........
As you can see, it is hopeless for black to persist in this attempt to escape, because eventually, this shicho leads to the edge of the board.
.....OX... <--- even if black plays the next step in the shicho,
....OXXO.. he still only has one liberty, and is captured.
...OXXO...
..OXXO....
.OXXO.....
..OO......
..........
However, black could persist if there was a ladder breaker present...
.......... .....O....
.......X.. <--- ladder ....OXXX.. <--- black escapes
.......... breaker ...OXXO...
..O....... ..OXXO....
.OXX...... .OXXO.....
..OO...... ..OO......
.......... ..........
Serious players read this out ahead of time, and won't persist in trying to escape if there is no chance of escaping, and likewise, one would not persist in trying to capture by shicho if there is a ladder breaker present.
The ability to read ladders before making moves is one of the fundamentals of go strategy.