GPU is short for Graphics Processing Unit; traditionally used to enable PCs to display advanced 3d graphics for gaming but they have also been repurposed to mine cryptocurrency.
Bitcoin (BTC) and other early cryptocurrencies used to be mined only using CPU’s but subsequent developments in mining software eventually led to miners moving over to GPU’s since a GPU can mine cryptocurrency faster and more efficiently than a CPU.
The reason for the increase in efficiency and mining power compared to a CPU is thanks to the different architecture of a GPU and the ability to install multiple GPUs in a computer or mining rig which is in contrast to CPU’s which are limited to only 1 CPU per computer or mining rig.
A GPU is composed of hundred or thousands of processing cores that though slower in overall speed compared to a CPU can process more overall work thanks to their sheer number. GPUs are also publicly available and anybody who wishes to mine using their computer can easily do so due to the retail availability of GPUs.
Miners of older blockchains like Bitcoin (BTC) have now moved on to ASIC’s ( Application-Specific Integrated Circuit ) which are more tailor made for cryptocurrency mining and can provide even greater efficiency and mining power versus GPUs. One issue with ASICs is that this means a centralization of mining power with professional miners and mining pools because only they can afford, run and maintain ASICs.
To combat this centralization, newer blockchains like Ethereum and Monero have incorporated a feature in their protocol called ASIC resistance which prevents ASICs from being used to mine on their blockchains.