Scalable hardware may refer to a single computer system, a large network of computers, or other computer equipment. The scalability of a single computer, such as a workstation, depends on how expandable the computer is. In this context, the words "scalable," "expandable," and "upgradable" may be used interchangeably. For example, a computer that has multiple drive bays has scalable disk space, since more internal storage devices may be added. A computer that includes multiple PCI slots has scalable graphics and I/O capabilities since PCI cards may be added or upgraded. A scalable network should be able to support additional connections without data transfers slowing down. In each instance, scalable hardware can expand to meet increasing demands.
Scalable software typically refers to business applications that can adapt to support an increasing amount of data or a growing number of users. For example, a scalable database management system (DBMS) should be able to efficiently expand as more data is added to the database. Scalable Web hosting software should make it easy to add new users and new Web hosting accounts. They key is that the software "grows" along with the increased usage. This means scalable programs take up limited space and resources for smaller uses, but can grow efficiently as more demands are placed on the software.
The scalability of hardware and software is important to growing businesses. After all, it is typically more economical to upgrade current systems than replace them with new ones. While all hardware and software have some limitations, scalable equipment and programs offer a long-term advantage over those that are not designed to grow over time.