Black 3 is not a good move, because it needlessly strengthens White’s position. It reinforces Black’s position too, so it may not look like a major sin. However, the exchange of Black 3 and 5 for White 4 and 6 strengthens White much more than it strengthens Black’s position.

 

In this case, the meaning of Black 1 is to split the White stones and, if possible, attack the marked White stone. By attaching in this fashion, he makes White stronger, but he also strengthens his own stones in order to establish a base.

 

The moves through 13 are a joseki. You will often find different variations of this joseki: in particular, playing 13 before 11. However, the moves through 13 are the simplest and the safest to establish a base in the corner.
As you can see, attaching to a stone can have different meanings and implications. Let’s expand on this a little further. Do you know this neat trick of an acrobat walking up one step against a wall to do a wall flip? If you do not know what I mean have a look at this short video: Brisbane Freerunner preview . In the video, Callum uses the strength of the wall as a springboard to cause an equal reaction in the opposite direction. That way he gathers enough momentum to make a backward flip. In go, we do that all the time, only it does not look so spectacular—but the results can be. Here is an example.

 

White has just invaded with the marked stone. How would you attack it?

 

We already know this by now—attaching to a stone you want to attack usually doesn’t work out well. Black 1 is an example of an attachment. White will play hane at 2 or at 4. In this example he plays 2. In the moves through 6, White has escaped; and worse, Black’s marked stone is severely weakened. This is very bad for Black but sadly it happens a lot in handicap games.

 

Solution 1

Solution 1

This is a situation you will probably encounter some time when you play the sanrensei opening and make a pincer with 1. Sometimes White will make a double kakari with 2. Now you have to decide which stone you want to attack. If you want to attack 2, the thing to do is to attach with 3. The moves through 9 are virtually forced. As you can see, attaching with 3 neutralizes White’s stone at 2.

 

On the other hand, Black can also attach with 3. The moves through 8 form the starting point of a variety of joseki patterns. Next Black can choose between A, B, and C. It gets quite complex after that, and all of the variations have pros and cons. However, the bottom line is that even if Black gets an even result locally, his stone at 1 is a little too close to Black’s wall. Most of the time, diagram 4 is a better way for Black to play.
To recapitulate, Black plays against the stronger stone, or more accurately, the stone he doesn’t mind strengthening. By attaching against White’s stone, he makes it stronger, but this also strengthens his own stone. Black uses that strength in turn to attack the weaker stone. This is called a leaning attack. You could also call it a diversification attack.

 

Please try to remember what we talked about last week. We discussed how it wasn’t a good idea to attach against stones you wanted to attack. We concluded it was better to attack from a little distance. I hope you agree that the leaning attack does exactly that, as it attacks the targeted stone from a distance.
In general, you don’t want to attach against a weak stone, but you don’t mind doing so with a strong stone if it helps you to become stronger and/or build momentum.