What was ostracism in ancient Athens?

Ostracism was an Athenian practice in which citizens voted on pottery shards, called ostraka, to decide whether someone should be sent into exile. If enough votes were cast against one person, that individual had to leave Athens for 10 years, though property was usually not confiscated. The system was introduced in the early 5th century BCE and was intended as a safeguard against political domination by powerful figures. It was not used for ordinary crimes but for perceived political threats. The practice is one of the most distinctive features of classical Athenian democracy.