Bitcoin was first mined in 2009 on a standard laptop CPU. Within a few years, miners had migrated to graphics processing units for their superior hashing efficiency, then to field-programmable gate arrays, and by 2013 to application-specific integrated circuits purpose-built for Bitcoin mining. Each hardware generation rendered the previous one unprofitable, because the proof-of-work mechanism adjusts difficulty to maintain a ten-minute block interval regardless of total network computing power. Better hardware does not reduce the network’s energy consumption; it raises the difficulty floor, and the total energy expenditure grows with investment.