An unbalanced corner is a corner with a single stone which is not on the diagonal line of symmetry. Of the common opening moves, the 3-3 and 4-4 points are balanced, while the 3-4, 3-5 and 4-5 points are unbalanced. When there are no open corners left, playing in an unbalanced corner is generally preferred to other moves, the main alternative being moves along the side.
through is one of the more popular fuseki's in use today. After occupying the four corners, there are two unbalanced corners on the board. Black plays an enclosure in one of them, and white then approaches the other one.
Another very common situation is the Orthodox Fuseki, still popular in professional play:
is often at a, is sometimes at b. For examples of professional games where this occurs see 11th Nongshim Cup. Some other examples with early unbalanced corners: