When we hear the terms the cloud or cloud
computing, we tend to think vaguely of the Internet. That is not entirely
wrong, but the two are not the same thing.
The Internet had existed for decades before people began
routinely talking about “the cloud.” What changed was not the network itself,
but increasingly what we were asking the network to do for us.
For years, using software usually meant installing it on a
particular computer. You bought a program, loaded it onto the machine, and
stored the files you created locally. The computer contained both the
application and, in most cases, the work produced with it.
Cloud computing began loosening that relationship.
Applications, storage, processing power, and other computing
resources could increasingly be provided remotely. Instead of asking What
software is installed on this computer?, users could simply open a browser,
sign in, and access a service running somewhere else.
The change can seem almost trivial because it happened
gradually. Email moved into browsers. Documents could be stored online rather
than on a hard drive. Music libraries became accessible from multiple devices.
Businesses began using software without installing and maintaining it on every
employee’s computer.
What disappeared was not software, but the requirement that
the software, the data, and the user all occupy the same machine.
SaaS, PaaS and IaaS
Cloud services are commonly divided into three broad
categories.
- Software as a Service (SaaS) is the form most ordinary users encounter. The provider runs the application, while the user accesses it through the Internet. Web-based email, collaborative office software, and many business applications follow this model.
- Platform as a Service (PaaS) provides developers with an environment in which they can build and run applications without managing all of the underlying infrastructure themselves.
- Infrastructure as a Service (IaaS) goes one level deeper. Computing power, servers, networking, and storage can be rented as services rather than purchased and maintained as physical equipment.
The categories differ, but the underlying idea is similar: some
part of computing that once had to exist locally can now be provided remotely
and on demand.
That is why the cloud is more than another name for the
Internet.
The Internet is the network.
The cloud is what became possible when storage, software, and computing power no longer had to live on the machine in front of you.
