Focal point lenght

Focal point lenght is defined as distance between objective's optic center and focal point which is with propertly focused scene positioned on sensor. Focal point lenght is expressed in mm and it is directly connected to scene pich, which we can photograph. That way, 20mm focal point lenght we call wide angle because it catches wide angle scene, while the one of 200mm is narrow angle or tele, because it catches narrow angle scene. Normal display of scene that we see with our eye is at approximately 50mm focal point lenght on 35mm standard, so everything beyond that we call tele, and everything below that wide andgle area.
Division of focal point lenghts:
< 20mm Super wide angle
24mm - 35mm Wide angle
50mm Normal angle
80mm - 300mm Tele
> 300mm Super Tele

Scene with 28mm lens

Scene with 70mm lens

Scene with 200mm lens

Graphical explanation of focal lenght and angle of view