concurrency results from any of the functionsthus the delay may be negligible (although there will typically be some small delay as each process is set upthis is shown graphically below parallelism distinction its often made in computer science between concurrency and parallelism in concurrencyseparate independent tasks are performed potentially at the same time in parallelisma large complex task is broken down into set of subtasks the subtasks represent part of the overall problem each subtask can be executed at the same time typically it is necessary to combine the results of the subtasks together to generate an overall result these subtasks are also very similar if not functionally exactly the same (although in general each subtask invocation will have been supplied with different datathus parallelism is when multiple copies of the same functionality are run at the same timebut on different data some examples of where parallelism can be applied includea web search engine such system may look at manymany web pages each time it does so it must send request to the appropriate web sitereceive the result and process the data obtained these steps are the same whether it is the bbc web sitemicrosoft' web site or the web site of cambridge university thus the requests can be run sequentially or in parallel image processing large image may be broken down into slices so that each slice can be analysed in parallel