The 3-5 or 5-3 point (Japanese: mokuhazushi) is a common first play in the corner.
In practice we arrive at 3-5 point openings in one of two ways:
Black chooses the 5-3 play as the first move in the corner. White answers at (depending on circumstances a and b are other common alternatives for White).
We call here the low approach. We call the move a the high approach. The move at b is called here on SL the 3-3 approach (whether or not it is more of an approach or an invasion).
Black starts with a 3-4 play at . White plays the low approach at
. If Black answers this play we move into the realm of 3-4 point openings. If however, Black plays elsewhere then we arrive at the same situation as the first diagram (but with the colors reversed). In effect, White has played 5-3 at
and then Black has approached at
. See tenuki joseki for more.
Such a transposed route is a much less probable way to arrive at the high approach or 3-3 approach variations. That's because the corresponding tenuki plays are much less advisable.
Ishida has this to say about mokuhazushi:
The 5-3 point is an interesting play. By its nature it cedes the corner to the opponent. In exchange it looks for benefits on the outside either along the top, down the left side, or both. Since the best way to accomplish this will depend on the rest of the board, many different joseki have been developed over the years.
For example, Ishida gives a through i as Black's possible responses when White plays the approach at :