What are the meanings of a, B and C of quadratic functions of one variable? For example, a represents the opening size and function image opening direction, B, C represents what?

What are the meanings of a, B and C of quadratic functions of one variable? For example, a represents the opening size and function image opening direction, B, C represents what?

B = 0, even function
C is the ordinate of the intersection of the parabola and the y-axis