You can specify geometric constraints between 2D objects or points on objects. When you later edit the constrained geometry, the constraints are maintained.
Thus, using geometric constraints, you have a method of including design requirements in your drawing.
For example, in the illustration below, the following constraints are applied to the geometry.
The geometry of the above design is not fully constrained. Using grips, you can still change the radius of the arc, the diameter of the circle, the length of the horizontal line, and the length of the vertical lines. To specify these distances, you need to apply dimensional constraints.