Crito
The dialogue takes place in Socrates' prison cell, where he awaits execution. He is visited before dawn by his old friend Crito, who has made arrangements to smuggle Socrates out of prison to the safety of exile. Socrates seems quite willing to await his imminent execution, and so Crito presents as many arguments as he can in order to persuade Socrates to escape. On a practical level, Socrates' death will reflect badly on his friends--people will think they did nothing to try to save him. Also, Socrates should not worry about the risk or the financial cost to his friends; these they are willing to pay, and they have also arranged to find Socrates a pleasant life in exile. On a more ethical level, Crito presents two more pressing arguments: first, if he stayed, he would be aiding his enemies in wronging him unjustly, and would thus be acting unjustly himself; and second, that he would be abandoning his sons and leaving them without a father.
Socrates
Details about the life of Socrates are derived from both contemporary sources, and later ancient period sources. Of the contemporary sources, the greater extent of information is taken from the dialogues of Plato and Xenophon (both devotees of Socrates), and the testaments of Antisthenes, Aristippus, and Aeschines of Sphettos, and the lesser from the plays of Aristophanes. Later ancient period sources include Apollodorus of Athens (alive during the second century BC), 
Cicero (alive 106–43 BC), and Diogenes Laërtius (alive probably in the earlier half of the third century AD).