Acronym for “graphical processing unit”. This is an early generation technology used for bitcoin mining. Miners found that GPUs could hash algorithms on the Bitcoin network far faster than CPUs leading to the first major shift of bitcoin mining hardware. In the formative days of bitcoin mining, bitcoins were mined with regular computers. Soon after, it was discovered that the GPUs used for gaming were more efficient. Most miners switched to GPUs before transitioning to ASICs.
Malone, J.A (2015). Glossary of Bitcoin Terms and Definitions. United States: Lulu Press, Inc