Cloud computing is the use of various services, such as software development platforms, servers, storage and software, over the internet, often referred to as the "cloud."
In general, there are three cloud computing characteristics that are common among all cloud-computing vendors.
The back-end of the application (especially hardware) is completely managed by a cloud vendor.
A user only pays for services used (memory, processing time and bandwidth, etc.).

Services are scalable

• -Many cloud computing advancements are closely related to virtualization. The ability to pay on demand and scale quickly is largely a result of cloud computing vendors being able to pool resources that may be divided among multiple clients.
• -It is common to categorize cloud computing services as Infrastructure as a Service (IaaS), Platform as a Service (PaaS) or Software as a Service (SaaS).

You are probably using cloud computing right now, even if you don’t realise it. If you use an online service to send email, edit documents, watch movies or TV, listen to music, play games or store pictures and other files, it is likely that cloud computing is making it all possible behind the scenes. The first cloud computing services are barely a decade old, but already a variety of organisations—from tiny start-ups to global corporations, government agencies to non-profits—are embracing the technology for all sorts of reasons. Here are a few of the things you can do with the cloud:

• -Create new apps and services
• -Store, back up and recover data
• -Host websites and blogs
• -Stream audio and video
• -Deliver software on demand
• -Analyse data for patterns and make predictions

Most cloud computing services fall into three broad categories:

• Infrastructure as a service (IaaS), platform as a service (PaaS) and software as a service (SaaS). These are sometimes called the cloud computing stack, because they build on top of one another. Knowing what they are and how they are different makes it easier to accomplish your business goals.

Infrastructure-as-a-service (IaaS)

• The most basic category of cloud computing services is IaaS. With IaaS, you rent IT infrastructure—servers and virtual machines (VMs), storage, networks, operating systems—from a cloud provider on a pay-as-you-go basis.

Platform as a service (PaaS)

• Platform-as-a-service (PaaS) refers to cloud computing services that supply an on-demand environment for developing, testing, delivering and managing software applications. PaaS is designed to make it easier for developers to quickly create web or mobile apps, without worrying about setting up or managing the underlying infrastructure of servers, storage, network and databases needed for development.

Software as a service (SaaS)

• Software-as-a-service (SaaS) is a method for delivering software applications over the Internet, on demand and typically on a subscription basis. With SaaS, cloud providers host and manage the software application and underlying infrastructure and handle any maintenance, like software upgrades and security patching. Users connect to the application over the Internet, usually with a web browser on their phone, tablet or PC.

Selenium WebDriver

• The core Selenium technology known as SeleniumWebDriveris an upgrade to RC or a by-product of Selenium RC that comes as a positive support system for JAVA, C#, PHP, Ruby, Perl, Python, and JS programming languages. It helps browsers and web z3 applications become ever powerful and expansive with the use of JavaScript embedded within it. The first cross-platform testing framework is fit to create advanced test cases and control browser from the OS level. Being the successor of Selenium Remote Control, SeleniumWebDriverworks forward to hit the testing functions on multi-browsers (Firefox, Chrome, IE and Safari) and also assist testing on OS as like Windows, Mac, Linux, Android, and iOS.

Selenium 2 or Selenium Remote Control (Selenium RC)

• Merging of the complete Selenium WebDriver and Selenium RC results in the evolution of a new breed of application known as Selenium 2 up on which majority of the Top Selenium Projects runs.

Selenium Automation Testing Advantages over Other Testing Tools:

• - Saving the recorded test.
• - Exploratory testing facilitates bug clearance.
• - Generate Logs for monitoring stepwise testing.
• - Selenium 2.0 efficient in Flash & DB test procedures.
• - Apply keyword-driven & hybrid approach for Data Automation.
• - Offer ease-of-consolidation with popular Java build tools (Ant, Maven).
• - Enfold Selenium testing scripts in the Testing Frameworks of your choice (JUnit, TestNG).
• - Conduct rigorous regression automation on multi-platforms using favourite Programming Language (Java, PHP, C#, Ruby, Perl, Python).
• - Frequent Automation Testing Processes &Tools cut error-prone and repetitious manual testing practices along with the manual QA testers.
• - Preferred Selenium Automation tool blended with other frameworks (TestNG or JUnit, NUnit, Sikuli) for enabling image based testing, reporting services using HTML etc,.
• - Presence of JavaScriptTestRunner in Selenium auto-provides a programming interface for executing test cases that are well recognized
  on the web pages for delivering prompt results.