Imagine you have a 55 gallon drum that's completely airtight. You connect a hose to it and start pumping in air. Assuming all connections are stronger than the drum, eventually the drum explodes.
Now, instead of pumping air into the drum, what would happen if you started sucking air out of the drum? Eventually the air pressure outside of the drum would be greater than the pressure inside the drum and it would crush, or implode.
When a building is demolished, they bring down the building with explosives. They blow out the internals of the building and the collapse in on itself that is a type of implosions. Whereas if someone sets off a bomb to blow up a building that is an explosion.
An implosion is the opposite of an explosion in that the object collapses inward instead of outward. An implosion is caused by a lower pressure on the inside of the object or structure, and outside pressure causes it to collapse.
berael t1_iu9g74b wrote
An explosion is an object bursting outwards away from its center.
An implosion is an object collapsing inwards towards its center.