Why Is Keyboard Input Buffered?

Your computer is like the conductor of an orchestra.  But not only is
it the conductor, it also plays all of the instruments.  So when it
decides it wants to do a certain task, it has to switch to that task
and do it and then come back and be 'the conductor' again.  In other
words, it's very busy doing many other things.  

So if you hit a
key on your keyboard while it's off doing another task, your keystroke
would be lost.  So a buffer holds the key strokes until 'the conductor'
is ready to respond to them.

Your computer's central processing unit (CPU) is like the conductor of an orchestra.  Not only is it the conductor, but it also plays all of the instruments.  So when it decides it wants to do a certain task, it has to switch to that task, do it, and when it's done, it comes back and be 'the conductor' again.  In other words, it's very busy doing a great number of things.  

So if you hit a key on your keyboard while it's off doing another task, your keystroke would be lost.  So a buffer holds the key strokes until 'the conductor' is ready to respond to them.