cylinder = tube

cylinder = Zylinder
general syntax:

cylinder{<x₁,y₁,z₁>,<x₂,y₂,z₂>, r
          texture{ ... ... }
        }

In this <x₁,y₁,z₁> and <x₂,y₂,z₂> are the coordinates of the centers of the both ends and r is the radius.

The samples here:

// the white cylinder left side:
cylinder {<0,0,0>,<0,3,0>,1 scale <1,1,1> rotate<0,0,0> translate<0,0,0>
          texture{pigment{color White}
                  finish {ambient 0.15 diffuse 0.75 reflection 0.1 phong 1}}}
// the both violet cylinders in front:
cylinder {<2,0,0>,<3.5,2,0>,0.2 scale <1,1,1> rotate<0,0,0> translate<0,0,-1>
          texture{pigment{color Plum}
                  finish {ambient 0.45 diffuse 0.55 phong 1}}}
cylinder {<3.5,2,0>,<5,0,0>,0.2 scale <1,1,1> rotate<0,0,0> translate<0,0,-1>
          texture{pigment{color Plum}
                  finish  {ambient 0.15 diffuse 0.85 phong 1}}}
// the slice of a tree right:
cylinder {<0,0,0>,<0,0,0.5>,1
          texture{EMBWood1 scale 0.1
                 finish {ambient 0.15 diffuse 0.85 phong 1}}
           translate<5,2,3>}
// the white flat cylinder, shrinked in z-direction right:
cylinder {<0,0,0>,<0,0.2,0>,2 scale <1,1,0.5> rotate<0,0,0> translate<4,0,2>
          texture{pigment{color White}
                  finish {ambient 0.15 diffuse 0.75 reflection 0.1 phong 1}}}
// the chrome mirrored cylinder in the back:
cylinder {<0,0,0>,<0,6,0>,2 scale <1,1,1> rotate<0,0,0> translate<3,0,6>
          texture{Polished_Chrome
                  finish {reflection 0.7}}}

Hint: To construct a cylinder which is parallel to one of the axis of the coordinatensystem but not in zero position, this can be done in a more difficult way but also in an easier way:

The most times worse style:
Start and end point of the cylinder are definded by their final values
=> the length and the position is hard to understand!

cylinder{<4,2,2>,<4,2,5>,0.5
         texture{ ... ... } }

The better style much easier to understand is better done according to this
principle of construction:
1st step: modellizzing (length and radius) the body at zero and then
2nd step: moving the body to it's final position. In this case the instructions better to understand would be the following:

cylinder{<0,0,0>,<0,0,3>,0.5
         translate<4,2,2>
         texture{ ... ... } }

Descriptions and Samples for the POV-Ray Raytracer by Friedrich A. Lohmüller

Basic Geometic Objects

cylinder = tube