Born in Athens in 429BC and died in 347BC, just before the birth of Alexander the Great. Came from a very wealthy and aristocratic family with many involved in Athenian politics while Plato himself was never involved with politics. During his early days, he learnt a lot about Socrates about the ways of thinking and questions relating to topic.
After Socrates' death, Plato wrote everything he learnt about Socrates. He had his own ideas and philosophy with one of his works was called "The Republic". It describes what Plato thought would be a better form of government than the current government of Athens. He believed that the best people chosen to run government is more efficient than democracy.
He learnt a lot about the natural world and how it works. He thought that everything has a sort of ideal form. One of the ways Plato tried to explain one of his ideas was the famous metaphor of the cave. There are prisoners chained to the wall facing into the cave and cannot see anything outside the cave. They can however see the shadows of what is going on outside the cave. The prisoners will think if the shadows are real or not. If one prisoner escaped and saw what real people, trees, grass and plants looked like and told other prisoners in the cave, would they believe him or not?
The point is that like those stuck in the cave, humans think they understand the real world but because they are trapped in their bodies, they can only see the shadows of the wall. One of Plato's goals was to help people understand the world better by finding ways to predict and understand the real world even without being able to see it.