Scale Up (Vertical Scaling) - Scale Out (Horizontal Scaling)

Scale Up (Vertical Scaling) : Buy a New System and Increase the Hardware.
Scale Out (Horizontal Scaling) is done on two vectors
               a. Functional Scaling( Divide the tables depending on functionality into different databases)
               b. Sharding   (Same Functionality is divided into different databases i.e., adding one more dimension to the above Functional Group).

Both Horizontal Scaling approaches can be applied atonce as follows.