# Iteration vs Recursion

Iteration and recursion are two different programming paradigms, neither is a special case of the other:

Iteration involves repeating a process using state contained in loops. It maintains state explicitly through variables.

Recursion involves a function calling itself repeatedly on smaller inputs. It maintains state implicitly through the call stack.

Some key differences:

Iteration uses looping constructs while recursion leverages function calls.

Iteration explicitly changes state each loop while recursion passes new state via arguments.

Iteration can be converted to recursion by encapsulating loop state and logic in a function.

Recursion can be converted to iteration using a stack to emulate the call stack.

Iteration avoids call stack limits inherent to recursion.

Recursion makes some solutions more elegant and declarative.

So in summary, iteration and recursion are distinct and complementary paradigms. Iteration is not a special case or subset of recursion, and vice versa. They can solve similar problems through different mechanisms. Choosing the right approach depends on the specific problem, constraints and clarity of expression.