Question

What is a sonic boom

Answer 1

A sonic boom is a loud sound like an explosion. 

Answer 2

Sonic boom is a loud sound that is the result of an object (a jet) traveling faster than the speed of sound.  When the jet exceeds mach 1, the pressure difference at the front and at the back of the jet is very high.  This creates two loud sounds, one when high pressure difference builds up and one when it returns to normal.  This cause high explosion like sound. That is called boom.

These booms carry a lot of energy. since there are two sounds, it is called double boom.