Equihash 144_5 is a PoW mining algorithm, also known as Zhash. The most popular coin that uses this algorithm is Bitcoin Gold, as well as BitcoinZ. BTG switched to Equihash 144_5 on block 536200 on July 3, 2018. The reason for the switch was pretty common – to protect GPU owners from ASIC invasion.
BitcoinZBTCZ
Bitcoin GoldBTG