Available KBytes is the amount of physical memory available to processes running on the computer, in KBytes. It is calculated by summing space on the Zeroed, Free, and Standby memory lists. Free memory is ready for use; Zeroed memory is pages of memory filled with zeros to prevent later processes from seeing data used by a previous process. Standby memory is memory removed from a process`s working set (its physical memory) on route to disk, but is still available to be recalled.