Boundary Point

The boundary point is the point at the edge of a number line inequality.

The boundary point for the strict inequality $x>4$ is $4.$

Boundary Line

A boundary line is a line that defines the edge of an area. Usually, this refers to the line that splits a plane in half in the graph of a linear inequality. In the example above, the line $y=x$ is the boundary line of the non-strict inequality $y\le x.$

Boundary Curve

A boundary curve is the same as a boundary line in every way except that the word curve can be used to describe inequalities whose boundaries are not linear functions. In this example, the curve $y=x^2$ is the boundary curve of the strict inequality $y>x^2$