Benzene is a widely used industrial chemical. Benzene is found in crude oil and is a major part of gasoline. Its used to make plastics, resins, synthetic fibers, rubber lubricants, dyes, detergents, drugs and pesticides. Benzene is produced naturally by volcanoes and forest fires. In homes, benzene may be found in glues, adhesives, cleaning products, paint strippers, tobacco smoke and gasoline.
A system call is an interface between a user-space application and a service that the kernel provides. Because the service is provided in the kernel, a direct call cannot be performed; instead, you must use a process of crossing the user-space/kernel boundary.
Asynchronous Procedure Calls. An asynchronous procedure call (APC) is a function that executes asynchronously in the context of a particular thread. When an APC is queued to a thread, the system issues a software interrupt. The next time the thread is scheduled, it will run the APC function.n APC generated by the system is called a kernel-mode APC. An APC generated by an application is called a user-mode APC. A thread must be in an alertable state to run a user-mode APC. Each thread has its own APC queue.