The tools on the Grid toolbar and the Grid menu can be used to display the grid, size it, and change its origin.

Display Grid

Hotkey: Alt + G
                             

Displays or hides the grid. This command is a toggle function.

Double Grid

                            
Doubles the spacing of the grid, making it less dense.

Halve Grid

                               
Divides the spacing of the grid in two, making it more dense.

Set Grid Origin

                               
Select the new origin for the grid, or enter coordinates in the Coordinate Fields. You can use Set Origin to align the grid to a particular point, then use the grid to set future distances.