Mnemonic is a learning and memory technique that aids in better retention and retrieval of information stored in the human brain. With mnemonics, elaborate cues or images are used to make memorization and recall easier. (1)
The word, mnemonic, is derived from mnēmonikos after translating it from the Greek, μνημονικός, into the English alphabet. Related to Mnemosyne, Greek goddess of memory, both words were derived from μνήμη, mnēmē or mnimi, meaning remembrance or memory. Mnemonics is also synonymous with the art of memory. (1)

I Call Her Mnimi | http://www.AboutMnimi.com
2 types of memory
According to ancient Greeks and Romans, there are two types of memory:
- Natural memory – used instinctively by people as it is inherent
- Artificial memory – developed through learning and practice of mnemonics
Reference:
(1) Mnemonic. (2018, December 23). In Wikipedia. Retrieved December 29, 2018, from https://en.wikipedia.org/wiki/Mnemonic.