Systematic Joseki 4-4 3-3
Keywords: Joseki
Summary - Joseki - San san under Hoshi in a general case.
The very fact of it being joseki is doubtful. Although often seen in beginer games it shouldn't be played at the very early stages as the thickness and therefore influence gained by Black from the early invasion is superior to the territory gained by White.
The attachment at a is a natural continuation exchanging thickness for territory. The key issue here is which side to block.