An activated grid helper object creates a true plane in 3D space. No matter how small an activated grid object appears on the screen, its plane is effectively infinite, just as if it were a plane of the home grid. However, you can view a given grid object in different ways.
You can adjust the visible plane of a selected or activated grid object on the Modify panel.
To set the display plane:
The grid rotates in world space to display the corresponding plane, always based on the grid's local axis.
You can move or rotate a grid, either before or after setting its display plane.
You can set the view in any viewport to an orthographic view as well as the display view.
To set grid view:
The viewport now shows this view of the grid.
You can set different viewports to different views of the grid. Objects are always created on a view's orthographic grid, even if you rotate the angle of view. In other words, you can set up a convenient view and still construct on the chosen plane.
You can deactivate a grid object in any of the following ways:
When you deactivate a grid object, any viewports based on that grid switch to the corresponding orthographic view. For example, a Grid (Front) viewport becomes a Front viewport. A Grid (Display Planes) viewport always switches to Top view, regardless of the currently displayed plane.