PUBLIC CLOUD
The most recognizable model of cloud computing to many consumers is the public cloud
model, under which cloud services
are provided in a virtualized environment, constructed using pooled shared physical
resources, and accessible over a
public network such as the internet. To some extent they can be defined in contrast to
private clouds, which ring-fence
the pool of underlying, computing resources, creating a distinct cloud platform to
which only a single organization has
access. Public clouds, however, provide services to multiple clients using the
same-shared infrastructure.
The most salient examples of cloud computing tend to fall into the public cloud model
because they are, by definition,
publicly available. Software as a Service (SaaS) offerings such as cloud storage and
online office applications are
perhaps the most familiar, but widely available Infrastructure as a Service (IaaS) and
Platform as a Service (PaaS)
offerings, including cloud based web hosting and development environments, can follow
the model as well (although all
can also exist within private clouds). Public clouds are used extensively in offerings
for private individuals who are
less likely to need the level of infrastructure and security offered by private clouds.