Prefetching in computer science is a technique for speeding up fetch operations by beginning a fetch operation whose result is expected to be needed soon. Usually this is before it is known to be needed, so there is a risk of wasting time by prefetching data that will not be used. The technique can be applied in several circumstances:

• Cache prefetching, a speedup technique used by computer processors where instructions or data are fetched before they are needed
• Prefetch input queue (PIQ), in computer architecture, pre-loading machine code from memory
• Link prefetching, a web mechanism for prefetching links
• Prefetcher technology in modern releases of Microsoft Windows
• Prefetch instructions, for example provided by
  • PREFETCH, an X86 instruction in computing
• Prefetch buffer, a feature of DDR SDRAM memory
• Swap prefetch, in computer operating systems, anticipatory paging