Dash (DASH), formerly known as Darkcoin, is a decentralised, open-source, digital cryptocurrency based on the Bitcoin project.
As its primary focus is on effective and instant payment, Dash offers stronger transaction privacy and anonymity, while its software is more resistant to mining with specialist hardware. Better privacy is achieved through a technology called Darksend, a coin-mixing service that combines identical inputs from multiple users into a single transaction with several outputs which obfuscates the flow of funds. Dash is also using X11 algorithm which employs a sequence of 11 rounds of hashing for its POW.
Read more here: https://www.dash.org