Full Idea
Besides a theory of truth of his own, Tarski developed a theory of theories of truth.
Gist of Idea
Tarski had a theory of truth, and a theory of theories of truth
Source
report of Alfred Tarski (The Concept of Truth for Formalized Languages [1933]) by Stephen Read - Thinking About Logic Ch.1
Book Reference
Read,Stephen: 'Thinking About Logic' [OUP 1995], p.22
A Reaction
The famous snow biconditional is the latter, and the recursive account based on satisfaction is the former.