What is Plato's Analogy of the Cave and its significance for philosophers?

With Plato’s analogy of the cave I find it is really useful to understand it visually, so I’m going to draw a diagram of the cave as I explain it. The useful thing about this is that when it comes to revising you can then just reproduce the drawing which rings the changes from note writing and helps provide a visual hook which you can draw on in the exam. So before we begin dissecting the analogy let’s think about what Plato was getting at, why did he use this analogy? Well for Plato he thought that the majority of people live in ignorance and that as human beings we should strive to be freed from ignorance and enter the world of the forms in which we can achieve true understanding. Plato advocated philosophical thinking as a way to be freed from ignorance and enter the realms of higher understanding. To illustrate this he provided the allegory / analogy of the cave which has been used and interpreted in many ways since. 
There are some prisoners who have been chained inside a cave since they were born so it is the only reality they have ever know. They sit opposite the wall of the cave on which they watch these shadows. The shadows they name and classify and to the prisoners the shadows are completely real, for what reason do they have to doubt their validity? However, unbeknownst to them there is a fire burning behind them in the cave and infront of the fire is a pathway which is often used by passers by carrying certain objects. It is the passers by who cast the shadows which of course renders the prisoners understanding of the shadows illusory. One day one of the prisoners is released, he walks out of the cave and into the sunlight and is at once disorientated, however gradually he regains his senses and comes to see clearly the ignorance in which he has been living, he is able to determine objects from their shadows. 
It is important to have a very clear distinction of what the different parts of the cave analogy represent: the Prisoner represents those living in ignorance (the majority of human kind), the Cave represents the physical world in which we can be easily misguided and live under illusions, the shadows represent false understandings which misguide us, the sun is the source of all knowledge. The journey of the prisoner is crucial to understand: the movement from living in ignorance to in induction into the world of the Forms and true understanding.