Short for asynchronous; describing computer operations that don't happen at the same time or don't require waiting for a previous operation to finish.
Modern abbreviation of asynchronous, which comes from 'a-' (not) + 'synchronous' (happening at the same time). This computing term became popular in the late 20th century as programmers needed shorthand for this increasingly common concept.
Async is the reason you can type an email while your web browser downloads a video in the background—instead of making your computer wait for one thing to finish before starting another, async lets multiple things happen simultaneously!
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