Scalability is the benefit of cloud computing that allows increasing or decreasing resources to meet
the predictable workload. Scaling can be horizontal (scaling out) when you provision additional resources to
function together as one unit, like adding additional virtual machines (VMs), or vertical (scaling-up) when you
increase the capacity of existing resources, such as by adding more CPUs or memory to VMs.
Elasticity is the benefit of cloud computing that allows the automatic increase or decrease of resources to
meet spikes and drops in demand. The distinction between scalability and elasticity is that the latter is
always done automatically to meet sudden bursts in capacity demand, while the former addresses more
predictable and even planned demand and workload requirements.
Agility is the benefit of cloud computing that enables speed and flexibility in the allocation and deallocation of
required resources. It allows the deployment of required resources and services in minutes without manual
administration of provisioning or de-provisioning processes.
High availability (HA) is the benefit of cloud computing that keeps resources and services functioning for
long periods of time. Cloud service providers typically offer a service level agreement (SLA) that guarantees
HA or uptime of resources and services as a percentage.