3-3 point
The 3-3 point is a good point, in that it makes territory in the corner, but it is still quite low and makes for a slow development. 三三就是在角上纵横数都是第三条线的位置。
However, a play on the 3-3 point in itself can be considered as decisive: no immediate further play is required to settle the corner. AlphaGo showed that 3-3 point is important and it is popular now to intrude there.
The popularity of 3-3 point openings in professional go has increased and decreased according to fashion, since they were first played in the 1920s (see New Fuseki Era, Shinfuseki post).
For White, the shoulder hit at e, taking influence in the centre, is quite common, but he can also play a kakari at b, c or d. An approach at ''a'' is not so good, in general.
If you later wish to develop a 3-3 point stone, a keima to a or ogeima at b, on the fourth line, are most often used. Also possible are c and d.
See also