Principaled BSDF in Blender what does it mean?

[darknkreepy3#]

Principaled BSDF
Bidirectional Scattering Distribution Function

It's a shader you might previously call a texture on a surface like wallpaper but so much more, it can use image textures to create the layers that are in a Principaled BSDF but also fractal algorithms, color ramps and a mixture of other processes we don't normally see as a surface, ergo "shader" is a new term.

It uses nodes to combine shaders together to create this type of modular maybe metaphor to an equalizer on a stereo system but even more. It's visual programming to create very versatile systems but you can start very simply to understand it one step at a time.