They were no longer threatened by Persia and could get back to their usual occupation of fighting each other.
It removed the Persian attempt to incorporate the Greek city-states into the Persian Empire.
The Greeks stood their ground and fought for their freedom against the Persians. Their victory caused the Greeks many lives.
In 490BC when Pheidippedes, a Greek messenger, ran from the Battle of Marathon, to Athens to proclaim the Greek victory over the Persians
The Greek won through superior sea (Salamis) and land (Plataea) tactics.
Greece was strongest when city-states banded together.
They were able to get back to their usual occupation of fighting each other.
Marathon was not a war, it was one battle in a 50-year war between Persia and the Greek city-states. The most important battles were Salamis, Plataea and Mycale. The significance of Marathon is that it was the first time that the Persians were defeated, and this Athenian victory showed to the other Greek city states, after nine years of Persian victories, that the Persians could be beaten.
The Persians decided to bring all the Greek cities under control to enforce peace. They invaded in strength ten years later.
The battleground where the Athenians defeated the Persians. The messenger who was sent to deliver the message of victory, collapsed and died.
The Spartan Admiral Eurybiades led the Greek naval contingent to victory over the Persians at the sea battle of Salamis .
Pheidippides , who announced the Greek victory over the Persians at the battle of Marathon . You can look to the related link below for additional information .
It stopped any further Persian expansion of control to the west and developed the virtue of freedom over tyranny.