How does S.M.A.R.T. work?

A special program inside the disk constantly keeps tracking the condition of a range of the vital parameters: driver, disk heads, surface state, electronics, etc. At the present time, S.M.A.R.T. technology is able to predict about 30% of all hard disk problems. However, to use this information, you firstly have to retrieve it from the disk and analyze it by using some specific software.