Demotic Greek is a way of writing and speaking the Greek language that people in Greece used a long time ago, like when your grandpa or great-grandpa was a kid. It was used from about 800 BC to 300 BC.
In Demotic Greek, people used simpler words and shorter sentences than they did in the older Greek language. It was a language that normal people could understand and use in daily life.
Back then, they wrote in funny-looking letters that were different from the ones we use now. They wrote on pieces of animal skins called "papyrus" or on walls and rocks.
Nowadays, we don't really use Demotic Greek anymore. Today, we use the modern version of the Greek language that is taught in school and used in books and newspapers. But it's still important to learn about the history of our language and how it has changed over time.