Carbocation rearrangement , Prediction of Unexpected Product.

In case of organic reaction , mechanism is the key of success .
Organic reactions are of three types -
(a) Addition Reaction
(b) Substitution Reaction
(c) Elimination Reactions

All the above mentioned reaction involve the use of Electrophile & Nucleophiles.
In most of the "electrophilic" reaction we get unexpected Products.
Lets understand the formation of Unexpected Products by " Carbocation rearrangement ".
Note - Following Video explains all about carbocation rearrangements -