Custom Core MVC Folder Structure or special category

Hi

i know some folders in Core Mvc or in MVC Asp.net ....  we have Controllers ,Model ,Views , Share ,Content , ...

 but in some pdf for Example in adam freeman PDF (Pro Asp.net Core MVC ) i saw he used   Infrastructure folder  and Concrete Folder and Abstract Folder ..

i dont know what is  " Infrastructure folder  and Concrete Folder and Abstract Folder" ? when i should use them ?  and which file or class i should put in that folders ?

and finally is there any Custom Core  MVC Folder Structure or special category that i have use in My Project , Please Explain it for Me ..

Tanks