As we have seen, for a system to be considerably scalable, it must still perform well under increasing load. A good scalable system would also reduce the need of having to redesign the system in front of this kind of scalability problem, which we can convert into business gains, avoiding possible financial loss to the company or decreasing the customer's confidence.

To know the scalability of your system, you must first understand its capacity, which is defined as the maximum number of processes or users a system can handle without losing capacity.

The question now is "How do we scale?" There are two ways to improve scalability: scaling vertically (scale up) and scaling horizontally (scale out).