Dash (formerly known as Darkcoin) is an open source peer-to-peer cryptocurrency that uses a system called Darksend to add privacy to transactions. It was rebranded from "Darkcoin" to "Dash" on March 25, 2015, a portmanteau of "Digital Cash".
Dash uses a chained hashing algorithm approach called X11 for the proof-of-work. Instead of using the SHA-256 (from well-known Secure Hash Algorithm family) or scrypt it uses 11 rounds of different hashing functions.
With chained hashing, high end CPUs give an average return similar to that of GPUs. Another side effect of the algorithm is that GPUs run at about 30% less electrical power than scrypt and 30% to 50% cooler, putting less stress on the computing setup and ensuring lower energy bills for miners.