A retargeting algorithm is a difficulty adjustment algorithm used by the Proof-of-Work blockchains to increase the effort and time required to solve a block problem and generate a new one. This algorithm makes mining a little harder and tasking like a puzzle and requires that miners do more than each time to mine.
A retargeting algorithm produces a value lower than the hash target. This algorithm is adopted by bitcoin to ensure miners have to work harder and put in more effort than when mining blocks in the ecosystem in 2009.
