In his life time, Plato was the author of thirty-six dialogues, discussing a variety of topics ranging from society, to religion, to science. These writings could be divided into early, middle, and late periods. His early dialogues generally focus on ethics, while those of the latter two periods expand beyond that. His most famous work was probably The Republic, where he talks about, among other things, government and how he believes society should be structured. Along with his writings, Plato founded a school in Athens known as The Academy. Though not much is known about the school, it would last for several centuries.
Just as important as the short-term, though, is Plato's long lasting influence. He was one of the earliest and most significant contributors to Western philosophy, especially in terms of science and religion. His ideas would be discussed over a wide period of time and topics, particularly through Aristolte, who is perhaps the greatest philosopher of all-time, and Plato's own student. As well, his religious ideas would be discussed by Christians early on and his thoughts on goverrnment were known by the framers who were attempting to establish the US Constitution.
Plato wrote the Apology and Plato's Republic. He wrote theories and doctrines that are still studied today. He had a great influence on science and religion. He also had a influence on Western thought and well known philosophers such as Aristotle and Augustine.