Someone please explain light refraction...simply!

I understand that refraction is the process of bending light but I don't understand how you would draw the process (in a diagram) nor why it occurs!

Someone please explain!

Thanks! xxoxx

Imagine light going from air into glass (for example) as a car going from tarmac onto sand at an angle. The wheel that hits the sand first will meet with the higher friction of the sand and experience more drag slowing that side of the car down. The three wheels on the tarmac will still be travelling at their initial speed and so will force the car into a curve, bending its path towards the normal of the sand/tarmac boundry. The same occurs with light travelling into an object with a higher refractive index (ie air to glass).
That's how we had it explained to us initially, as to why it occurs and stuff.

different substances have an assigned refractive index. refraction happens when light waves go from one refractive index to another refractive index. the light rays bend. kind of like throwing a ball at a wall, it glances off the wall and it's path bends to allow it to enter the next substance. refraction is talking about the path that the light rays must take.