Extrude

Extrude is the modifier for 2d splines or shapes .

And it  is the process of adding height to  a shape
( in a straight line along its Z axis)

To extrude a spline:-
Select a spline object

Apply an Extrude modifier

Enter an Amount value (amount of height of extrusion).

The spline is extruded. If the spline is a closed shape, then a cap of faces is built in the enclosed area by default.
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