What was the three most important results of the Persian Wars?

Answer 1

Persia returned to consolidating its empire in Asia, Athens emerged as the most aggressive power amongst the Greek city-states, and ensuing inter-city-state wars wars so weakened them that Macedonia was enabled to takeover the Greek world.

Answer 2

Persia gave up trying to impose peace on the Greek cities and agreed to leave them alone to go back to their usual fighting of each other.

Athens converted the anti-Persian league into an empire of its own and ended up in a major devastating war against the Peloponnesian League.