(;
AB[pd][pj][pp]
AW[cd][dq][nd]
TR[nd]
C[Black's response to the marked approach?

Source:
    American Go Journal, Vol. 33, No. 4, p. 20
    What's Wrong With That Move?
    Nakayama Noriyuki]
(;
B[pf]
C[Black should just make the simple one space jump, which doesn't strengthen White's stone and leaves Black many points to aim at.];
W[ic]
LB[kc:A][ld:B]
C[White can do something like pulling back here.  But White has weak points.  For example, Black can invade at A or B.]
)
    (;
    B[nc]
    C[Black should not attach here.];
    W[mc]
    C[Suppose White follows with this sequence.];
    B[oc];W[md];B[pf];W[ic]
    C[This result looks ordinary, but White is very grateful.  Why?]
    (;
    B[ec]
    C[For one reason, White's upper shape is strong after the top right sequence.  So if Black invades here, ...];
    W[dc];B[ed];W[df]
    C[... White squeezes the 2 stones.]
    )
        (;
        W[qc]
        C[For another reason, the top right has terrible aji.

If Black could secure a large territory in the top right, then everything would be fine.  But at the appropriate time, White might invade here.

The possible follow-ups are somewhat complicated, but generally, White has a ko, which Black is not happy with.  A couple variations follow to show some of the ideas.];
        B[qd];W[rd];B[re];W[rb]
        (;
        B[pb];W[qb]
        LB[pc:A]
        C[And Black has to worry about White's painful push at A.]
        )
            (;
            B[sd];W[sc]
            C[And White has a ko.  Ko threats in the opening a difficult to come by, but if White loses the ko, White has 2 moves elsewhere, which is enough for White.]
            )
        )
    )
)

