What is total internal reflection?

Dear, In case of a light ray passing from a denser to a lighter medium and incidents on the interface at an angle more than the critical angle between the two mediums, then no portion of the ray refracts into the lesser medium and the total ray reflects back to the denser medium and the reflection i

Hi, The complete reflection of a light ray reaching an interface with a less dense medium when the angle of incidence exceeds the critical angle.