The override modifier is required to extend or modify the abstract or virtual implementation of an inherited method, property, indexer, or event.

In this example, the class Square must provide an overridden implementation of Area because Area is inherited from the abstract ShapesClass:



abstract class ShapesClass
{
    abstract public int Area();
}

class Square : ShapesClass
{
    int x, y;
    // Because ShapesClass.Area is abstract, failing to override
    // the Area method would result in a compilation error.
    public override int Area()
    {
        return x * y;
    }
}