What is meant by subsidiary/delegated legislation?

Question

What is meant by subsidiary/delegated legislation?

and

why is there a need to have a subsidiary/delegated legislation?

Answer 1

Delegated legislation (also referred to as secondary legislation or subordinate legislation) is law made by an executive authority under powers given to them by primary legislation in order to implement and administer the requirements of that primary legislation.

And there is a need to have them because for example if the USA decide that they want to lower the smoking age, they may use subsidary legislation. because some states may have very high underage smoking age rates. (this is just an example)

Hopes this helps.