Quarter round

Quarter round, a term typically used in the flooring industry, is a convex molding that has a cross section in the form of a quarter circle. A variation is a base shoe, a quarter of an ellipse.
Typically used as a flooring joint between the flooring and the baseboard, quarter round is not a requirement for flooring, but in the United States, it is preferred due to its aesthetic appeal. It covers the uneven edge as flooring meets the baseboard.