Plato was an immensely influential ancient Greek philosopher, a student of Socrates, writer of philosophical dialogues, and founder of the Academy in Athens where Aristotle studied. Plato lectured extensively at the Academy, and wrote on many philosophical issues, especially politics, ethics, metaphysics, and epistemology. The most important writings of Plato are his dialogues. It is believed that all of Plato's authentic dialogues survive.
Socrates is often a character in Plato's dialogues. How much of any given dialogue is Socrates' point of view, and how much of it is Plato's, is heavily disputed, since Socrates himself did not write anything; this is often referred to as the "Socratic problem". However, Plato was doubtless strongly influenced by Socrates' teachings, so many of the ideas presented, at least in his early works, were probably borrowings or adaptations...