Asynchronous processing is a means of inducing parallelism in a single processor machine. Concurrency in asynchronous processing differs from concurrency in multitasking in a single CPU machine. While the latter involves synchronizing processes to access the same resource, asynchronous processing is genuinely simultaneous because processes access different resources at the same time. Asynchronous processing is possible only if one of the jobs doesn't require CPU time, so it usually refers to I/O, either network or disk. When it can be used, asynchronous processing greatly speeds up work. Some database vendors, including Sybase and Oracle, support asynchronous communication between client applications and servers.