Built in Shaders

Hello!
I have a question.

Thus when download the unity manually, there is a folder called Built In shaders, which logically contains a number of shaders. But inside this folder there are several files and no instructions, no how to install them or how to use them.

Does anyone know what they are for, and how to use them?

Sorry for my Goglenglish.

You don’t need to install them. They’re built-in.

The download is provided so you can study their source, in case you want to modify or build your own shader based on the built-in ones.