The idea of a spherical Earth appeared in Greek philosophy with Pythagoras (6th century BC), although most pre-Socratics (6th–5th century BC) retained the flat Earth model. Aristotle provided evidence for the spherical shape of the Earth on empirical grounds by around 330 BC. Knowledge of the spherical Earth gradually began to spread beyond the Hellenistic world from then on.

In the modern era, pseudoscientific flat Earth theories have been espoused by modern flat Earth societies and, increasingly, by unaffiliated individuals using social media.