What is an Android launcher?

What is it?
Does the word, “launcher” make any sense to you? If it doesn’t then
you may not know what one is, but you are using one every time you use
your Android mobile. Still not making any sense? let me give you an
example.

Have you noticed how each Android mobile manufacturer ships their
phones with a different type of Android. They are all the same at their
heart, but they look