The Drawing Grid Drawing option provides a different, more visual way to obtain snap points based on a grid when drawing new objects at Block and Surface levels:
Block when using any block level drawing tool (Partitions, assembly, Construction lines)
Surface when using any surface level drawing tool (Window, Subsurface, Hole, Door, Vent, Boundary conditions, Construction lines).
The Drawing Grid can be accessed when at block or surface level from the bottom left Drawing Options panel when adding a new object. See the screenshot below which shows the Grid in use at block level.
The Grid can be used in combination with Increment snap and the other Point Snap options.
See also: Increment Snap