Learn You a Haskell for Great Good says:
A typeclass is a sort of interface that defines some behavior. If a type is a part of a typeclass, that means that it supports and implements the behavior the typeclass describes.
Cats says:
We are trying to make the library modular. It will have a tight core which will contain only the typeclasses and the bare minimum of data structures that are needed to support them. Support for using these typeclasses with the Scala standard library will be in the
stdproject.
Let’s keep going with learning me a Haskell.