Ishida Volume 1

Small Knight Approach  

The small knight move 2 is the basic approach move to the 3-4 point stone. It has been in continuous use for over four centuries, according to reliable records, and has been regarded as the most effective approach move. It continues to be just as highly evaluated. However, the variations are limitless and new moves are constantly being discovered. This move is truly a treasure-house of joseki.

• The large knight approach (Ogeima Gakari)

Large Knight Approach  

This move 2 is not played on its own but when there are friendly forces backing it up. Its purpose is to prevent the opponent from playing a pincer. From the point of view of just the corner, this move accepts a loss, as it does not have much effect on the opponent's 3-4 stone and does not take much territory. However, it can be valid as part of a fuseki strategy. It was popular in the late 1950's and early 1960's but is not seen so much nowadays, having been replaced by the one-space high approach, with which it has points in common. This last comment is out of date as the large knight approach has made a strong come back recently particularly as a counter to the Kobayashi Fuseki.

• The two-space high approach

Two-Space High Approach  

2 is a light move. White is not concerned about corner influence but is satisfied if he can get Black to answer here, as this means preventing Black from making a corner enclosure, while keeping sente. From Black's point of view, there is nothing wrong with replying as White wants, while he can also try to make White answer him. This approach move was very popular in the 1910's and almost all the variations have been completely explored.

--DaveSigaty