Grids are two-dimensional arrays of lines similar to graph paper, except that you can adjust the spacing and other features of the grid to the needs of your work.
Using the home grid to position houses
Grids have these primary uses:
The home grid is the basic reference system, defined by three fixed planes on the world coordinate axes . The home grid is visible by default when you start 3ds Max, but can be turned off with an option in the right-click viewport menu. You can use any view of the home grid as a construction plane or you can create a grid object and use that as a construction plane instead.