Short answers, pulled from the story.
Athens is believed to have held the largest enslaved population of any Greek city, with as many as 80,000 slaves during the 6th and 5th centuries BC, or roughly three to four per household. A census ordered by Demetrius Phalereus between 317 BC and 307 BC returned a figure of 400,000 slaves in Attica, a number many researchers doubt.
Slaves in ancient Greece worked mainly in agriculture, along with mines and quarries, as domestic servants, and as craftsmen in workshops. Athens also used public slaves, called demosioi, as police officers, executioners, treasury clerks, and record keepers.
People became slaves in ancient Greece mainly through war, piracy, banditry, and organized trade, since a victor in war held absolute rights over the defeated. Athenians could also fall into a form of bondage through debt, until Solon's reform known as the seisachtheia ended debt bondage in Athens.
A slave in ancient Greece could gain freedom through manumission, a practice documented on Chios as far back as the 6th century BC. A slave could pay for their own freedom, sometimes with a loan called an eranos, and manumissions were later recorded in stone inscriptions at shrines such as Delphi and Dodona.
Spartan helots belonged collectively to the state rather than to individual citizens, unlike Athenian slaves, who were the property of individual masters or the state and could be bought, sold, or leased. Historians still debate whether Spartans also owned individually held chattel slaves.
Slavery in Greece continued under Roman rule from the 2nd century BC and then under Byzantine rule through the Middle Ages, before large-scale agricultural slavery gave way to serfdom. Under later Ottoman rule, from 1458 to 1830, Greeks were subjected to systems such as the devshirme, and the Chios massacre of 1822 led to the Ottoman Empire's first anti-slavery reform, the Firman of 1830.