A quadratic function is a polynomial function of degree 2. It has the general form f(x) = ax^2 + bx + c, where a, b, and c are constants.
Vertex: The highest or lowest point on the parabola formed by a quadratic function.
Axis of Symmetry: The vertical line passing through the vertex of a parabola.
Discriminant: In quadratic equations, it is b^2 - 4ac which determines how many solutions exist for the equation.