What do you understand by Controller and what are its primary functions? - Hard disk

What do you understand by Controller and what are its primary functions?

- Controllers can be considered to be an interface between the disk and the host computer.

- These days most of the Controller circuits are placed inside the Southbridge of the motherboard.

- The controller is also used for the following functions: Error code correction, Wear leveling. Bad Block, read scrubbing and disturb.

- SSD are comparatively expensive as compared to Simple hard disks.