A CPU miner is a person, or a piece of software, that mines cryptocurrency using a computer's central processing unit (CPU) rather than a graphics card or specialised chip. In Bitcoin's first year, all mining was done this way, but miners switched to GPUs from around 2010 and to ASICs from 2013, making CPU mining of bitcoin hopelessly unprofitable. Some networks deliberately keep CPUs competitive with ASIC-resistant algorithms: Monero has used RandomX, designed for general-purpose processors, since 2019, to keep mining open to ordinary users. The same accessibility makes CPU-friendly coins a favourite target of cryptojacking, where malware secretly mines on other people's computers.