guess the correct number; conversely, if miners drop out, then it gets easier to guess the correct number. This is called mining difficulty.
Back when crypto-assets first emerged some ten years ago, there were very few crypto-miners, so relatively little computational power was needed to guess the number problems correctly. As a result, the CPU (Central Processing Unit) of an average household computer was more than adequate for the job – but as more and more people joined the crypto-mining community, it became more and more of a race to find the right number – which meant that people were using ever more powerful computers.
The first major computer upgrade for crypto-asset mining was the use of GPUs (Graphics Processing Units), which were originally designed for gamers who played computer games with powerful graphics requirements (1 GPU = about 30 CPUs).
Then there was another power hike, with the introduction of FPGAs (Field-Programmable Gate Array), which were up to 100 times faster than GPUs.
Finally, the ASIC (Application-Specific Integrated Circuit) was introduced, and remains the industry standard today – principally because ASICs are designed specifically for crypto-asset mining.