Although hype and guesswork have surrounded the concept of cloud computing for a long time, it's more than a buzz term. As a result of increased exposure to portable devices such as smartphones, tablets and portable computers in the consumer sector, as well as changes in workplace use of home work, moving businesses, and personal tools, the use of centralized virtualized computing resources in the latter years. In fact, many of us in some form use cloud computing every day without realizing it, whether it's webmail or online gaming.
What is Cloud Computing
Cloud Computing describes a script in a general sense where the user (cloud client) uses a computer resource from a virtual environment (cloud) over the Internet. However, it may be contrary to the use of computing resources on the user's local machine, local area network, or other physical machines on other networks. Cloud services are generally operated by service providers that collectively provide extensive physical resources (eg, Multiple Servers between Multiple Data Centers) to create a service that users can use at any time (eg on Request) without hardware or software  If the service is subject to a charge, it may be offered on a payment when the user pays for the energy he actually consumes, similarly to electricity as electricity, where consumers can touch the national network (analogue over the internet) and simply pay what used.
There are a number of different services that are under the umbrella of the cloud computing and which conform to the above definitions, but are generally classified in three camps, depending on whether IaaS
is generally Infrastructure as a Service (IaaS) , cloud computing computing includes services that offer virtual physical computing resources, such as resources, such as server space, bandwidth, networking.
Outstanding examples of IaaS bids include cloud-based hosting, where Web sites are placed in virtual server partitions, which draws physical resources from multiple servers in multiple data centers. This idea can have concrete benefits such as cost-effective scalability – hardware resources are available on demand, so the customer only pays for what they use and does not limit their capacity
PaaS describes a proposal that includes the creation of a required operating environment required software created by the client for its own applications. In other words, PaaS also includes tools such as the solution package operating system, the server-side script environment, database support, and so on. Cloud clients often check the tools they are using on their own platforms, sometimes from a restricted list, and how they are configured, but all building blocks are provided by the service provider.
Cloud Hosting is an example of PaaS since many of the packages on the market are not just a virtual server for the user, but the whole platform, for example, a package of solutions for building and receiving a website. Other examples of PaaS include software development testing and development environments. Like SaaS, these services offer their customers greater collaboration and storage facilities for their customers when they use apps.
Software as a service (SaaS)
is a familiar form of cloud computing for most consumers. Describes an offer in which an Internet service or software service is available. This is an area that many large software and Internet companies, such as Microsoft, Google and Apple, are thriving since they all seem to follow the trend by removing locally installed (and sometimes incompatible) software for running applications  SaaS obvious examples include Google Docs and Microsoft Office 365 (which can be integrated with the software's traditional deployment), but cloud computing also includes other features such as webmail and online games that are entirely on the Internet
There are a number of cloud computing classes in SaaS and follow the same naming conventions as the desktop service (or virtual desktop computers where virtual desktop version of the computer is stored and accessible in the cloud) and the test environment as a cloud (TEaaS, which provides a central test for software testing)
Key controller and behind SaaS growth is the fact that cloud-based applications can be used from any physical location if they have an internet connection (such as ADSL or 3G) and any operating system running device. This independence from geographic and technological constraints allows personal users and employees not only to work on applications and files under any scenario, but only to work with limited restrictions and share these services