Synonymous to scaling. Computer system characteristic that is the ability to increase capability while retaining or increasing response time and throughput performance. Such a system can accommodate additions to its capacity and capabilities. On hardware, it is adding or increasing or improving hard disks, memory, or video boards .On software, it is supporting more network users, allowing a greater number of ‘hits’ from website visitors, or getting faster number crunching. Refer to extensibility and scaling.