why is a Solid State Drive (SSD) faster than a Hard Disk Drive (HDD)?

Hello and Good Afternoon Everyone,

           I have heard that a Solid State Drive (SSD) is much faster than a Hard Disk Drive (HDD).  With regards to why an SSD is faster than an HDD, I have not really been given any explanations.  That said, does anyone know why an SSD would have better speed performance than an HDD?

           Any shared thoughts to this question will be appreciated.

           Thank you

            George