What is genetic engineering?

What exactly is genetic engineering? Can someone explain to me what it means
and what it does?

This term is very easy to understand. Genetic engineering is the
manipulation of DNA to cause a living organism (any living organism) to
develop in a different manner than it would have without the manipulation.
This process is very similar to naturally occuring DNA mutations except that
in genetic engineering these mutations are deliberately created by a
scientist rather than by natural forces.