maido
This is a shape that occurs in a common joseki. As players of reasonable strength should be able to see, white needs to protect the cutting point at a.
However, if white plays above, black takes an excellent shape point, and white cannot be satisfied. The same will occur if white protects the cutting point with either of the tiger's mouth plays (marked a). White must use maido to gain a good result.
Here we see a generic side situation. Since it is black's turn, the marked stone is saved easily. For white to capture black, she must place a stone that interferes with the process by which black escapes.
As you can see above, all of the marked white stones kill black. There are many such combinations; these are just a few examples.
is the joseki move. As you can see, after the exchange
at a,
at b,
matches
in the fourth example in the previous diagram.
Imagist: I'm not actually sure what Maido is, beyond the explanation above. I was taught it by a dan player at a go tournament, but I never got a real definition from him. From his explanation, it seemed like it could be: 1) capturing by understanding the process of an escape from that capture or 2) various moves that work for the same purpose. If anybody knows more, please add to this!