What is total internal reflection

I know refraction is the bending of light when entering one medium to another. -bends towards the normal from less dense medium more dense medium (air to glass) and so opposite is also true..
BUT. What is total internal reflection? Is that, instead of bending when meeting a new medium, it instead reflects like that in a plane mirror? Or instead goes straight some how?

When light passes from a heavy to a light material it MUST bend away from the normal.

But if the angle of incidence is greater than the critical angle there is no possibility of bending at the amount required by snell's law.

At smaller angles SOME light is reflected and some refracted. As you approach the critical angle a greater percentage is reflected and less is refracted.

But by the time the critical angle is reached no light can exit the medium. Hence TOTAL internal reflection.

for u to understand wats total internal reflection u 1st hv to noe wat is critical angle. critical angle is defined as the angle of incidence in the optically denser medium 4 which the angle of reflection in the less dense medium is 90 degrees. for example i shine a light into a semi circular glass block at an angle it gets refracted out right? but if the critical angle is for example 49 degrees and i increase the angle of incidence beyond the critical angle, the light ray will be reflected back into the glass block instead of being refracted out of the glass block. This is known as total internal reflection.

it only takes places when the angle of incidence in the optically denser medium is greater than the critical angle.

to find the critical angle : SinC = 1 over N (C = critical angle, N = refractive index)