"Plato... stands at the head of our philosophical tradition, being the first Western thinker to produce a body of writing that touches upon the wide range of topics that are still discussed by philosophers today under such headings such as metaphysics, epistemology, ethics, political theory, language, art, love, mathematics, science, and religion." (The Cambridge Companion to Plato, Kraut pg. 1)
Aristocles was the original name given to Plato, and it is believed that Plato (or platos, meaning "broad"), is possibly a nickname given by his wrestling teacher to describe his physical attributes. The accurate dates of Plato's birth and death are not known for sure, however, it is generally accepted that he was born in Athens around 428 B.C., and died around 348 B.C. Knowledge of Plato's family is not entirely certain, but it is believed that Ariston was his father and his mother was Perictione, however, it is certain that he had two older brothers and a sister, Glaucon, Adeimantus, and Potone, respectively. Plato also had a half-brother, Antiphon, who was born of Perictione and her uncle, Pyrilampes, after the death of Plato's father. Plato was born of a very wealthy family who were equally politically active. Charmides, uncle of Plato, was a member of the Thirty Tyrants, a group of people who overturned the democracy of Athens in 404 B.C. Charmides' own uncle was the leader of the Thirty Tyrants. In addition to this political activity, it is also said that Plato's step-father was closely involved with Pericles. From this knowledge it is apparent that Plato's family, direct and distant, were associated avidly in Athenian politics. (Source)
Plato aimed to become a political figure in Athens, but, as a result of the tyrannical democracy in Athens, he was driven away from this aspiration. The execution of Socrates was also a result of the the tyrannical government, which, subsequently, was also an aspect to Plato's turning away from becoming a politician. Plato had many influences, however, the most notable was Socrates. Socrates journeyed throughout Athens on his journey of moral reform, gaining respectful followers as well as an equal amount of enemies, particularly the Sophists. Plato was comprised in this group of followers, and perhaps was the most loyal. Plato recorded dialogues of Socrates and other philosophical figures, which were discussions disputing commonly asked and not-so-commonly asked questions of moral values, for example, What is virtue? This is the question asked in Plato's Meno; the conclusion of this matter was never actually answered in the Meno. Plato's early work was mainly composed of dialogues of Socrates, all the way until his death. Plato recorded the conviction and trial, the awaiting of execution, and the actual execution of Socrates, in his Apology, Crito, and Phaedo. Other influences on Plato include Heraclitas(who took part in the shaping of Plato's view of the constantly changing rational world), Parmenides along with Zeno(who were, in fact, a great influence on Plato's ideology of Forms), and finally the Pythagoreans (who are included in various writings of Plato). Although Plato had several influences, it is anything but unclear that Socrates remained the utmost influential person in his development of philosophical beliefs. (Source 1, Source 2)
"The better reason derives from the nature of the Platonic texts. They are dialogues representing specific, named individuals in conversations with one another. Plato did not invent Athenians with names, demes, and kin; he wrote about real people - some of them still active and living in Athens - people with reputations, families, neighbors and political affiliations, people who show up elsewhere in the existing historical record: lampooned in comedies, called as witnesses, elected to office, being sold, marrying, buying property, traveling, dying. Socrates' society was not only a matter of institutions and ideologies, but a matter of actual people, individuals within a nexus of familial, social, and political relationships, without whom Plato's dialogues would be denatured." (The People of Plato: A Prosopography of Plato and other Socratics, Nails pg. XXXVII - XXXVIII)Plato wrote of real events happening in his time, in the sense of philosophical events mainly consisting of Socrates. Plato wrote many accounts of Socrates, and also just plain wrote of issues still asked in our modern culture. Plato wrote on political theory, moral values, the theory of Forms, and so on. Initially, Plato carried on the philosophical views of Socrates after Socrates' death, but as time passed on he developed his own views along with the development of the Academy. The Academy was the education system of Plato, created in 385 B.C., in which Plato used the dialogues of Socrates as discussion material. Although the Platonic dialogues of Socrates were significant in the works of Plato, namely the Apology, Plato had other great accomplishments, such as the Republic. The Republic is a highly influential writing of Plato; it effectively consists of the matter how to live a good life, different aspects of justice, justice within government, what is an ideal republic, and other matters. The Republic encompasses every belief that was held by Plato. Plato was a great teacher and, through his writings and education given through the Academy, left precedents who would carry out and expand upon the philosophy of Plato. One of the most well-known of Plato's pupils was Aristotle. (Source)
Aristotle was not born in Athens, the central point of philosophy, but was born in Stagira, Greece. In 367 B.C. Aristotle was sent to Athens to study at the Academy with Plato, and excelled as a great intellectual pupil. Although Aristotle excelled in the Academy, he opposed views and teachings of Plato, and left around 347 B.C. After the death of Plato, Aristotle was not designated as the person to be in charge of the Academy. Aristotle was a brilliant man; although he studied moral values and other philosophy, he took great interest in biology and science. (Source)
Now back to Plato. Plato's theory of "Forms" or "ideas" is his brilliant combination of Heraclitas' ideology - nothing is certain except that things change - and Parmenides' ideology - all change, motion, and time are illusions. Plato asked himself, Where was the truth? The result of Plato's reasoning was the concept of Forms. Plato described a cave in which a group of people had been born and were prisoner to. From birth these people had their backs turned toward the entrance of the cave, and could only look at the cave wall. At the entrance of the cave was a fire, and people would walk between the fire and the cave, casting shadows upon the cave wall which the prisoners were looking at. To the imprisoned group of people, the shadows were the real world, it was all they knew. The reason for this illustration was to show that the people looking upon the shadows would have an irrational view of the world, therefore acting irrationally. Although the people were imprisoned and had a false view of the world, they could search for something else, and escape imprisonment and find the entrance to the cave - the real world. This was the basic idea of Plato's Forms. (Source 1, Source 2, Source 3)
Plato was the first immensely influential figures through writings, accounts, dialogues, and documentations. Although using Socrates a guideline for his earlier thoughts, he developed his own ideologies. Plato had a different style of teaching than that of Socrates, in the sense that Socrates actually "taught." Socrates questioned the people, whereas Plato actually put his effort into teaching the people through a more systematical method, consequently developing the Academy. I'm not saying that Socrates didn't teach, I'm saying that he questioned and left the doors open for the people to figure it out themselves; he made them think and reason. Also, Socrates was seen as a gadfly in his society, while in contrast, Plato was seen as more of an educator. (Source)
Kraut, Richard. The Cambridge Companion to Plato. United Kingdom: Cambridge University Press, 1992.
Nails, Debra. The People of Plato: A Prosopography of Plato and Other Socratics. United States of America: Hackett Publishing Company, 2002.