Scalability:

Scalability is the competence of the system to adapt to increased service load. A scalable system will respond more gracefully to increased load than a non-scalable one. First, its performance degrades additionally moderate and second; its resources take a longer time to accomplish a saturated state. A scalable system must have the potential to grow without having to resort to expensive design modifications. Secondly adding up machines to the distributed system shouldn't clog the network. Therefore scalable design should withstand high service load, contain the growth of the user community, and make possible simple integration of added resources.