 A cylinder is the set of all lines passing through a curve and parallel to a given line. The given line is called the axis of the cylinder and the given curve is called the base curve or directrix of the cylinder.
 A cylinder whose base curve is a circle and whose axis passes through the center of the circle and is perpendicular to the plane of the curve is called a right circular cylinder.
 The equation of a right circular cylinder with base curve's radius is r and whose axis z = 0 passes through (0,0,0) is
x^{2} + y^{2} = r^{2}.
 The equation of a right circular cylinder with radius r and axis
(x  a)/α = (y  b)/β = (z  c)/γ is [(x  a)^{2} + (y  b)^{2} + (z  c)^{2}  r^{2}](α^{2} + β^{2} + γ^{2}) = [(x  a)α + (y  b)β + (z  c)γ]^{2}.
