From SaaS to cloud computing - historical review
Until a decade ago many entrepreneurs encountered high entry barriers, on their way to start a business, derived from the need to build expensive computing infrastructure, beyond the specific investments and the expenses, which were required to establish the business 

Businesses of all arc areas, whether a software development startup companies, whether sales offices or computerized production floors in factories were forced to do large investments which were required for establishing computing infrastructure, including: purchasing of servers, laying communications lines, hosting, security, backups and licensing for software.
These acquisition costs, which accompanied the construction phase, of the business, were replaced with heavy maintenance costs, which were required for its regular operation.

"Software as a service" (SaaS)
At the beginning of the decade began to emerge Outsourcing Services, especially in the field of "software as a service" (SaaS). These have brought a revolution in perception, which was prevalent until then, that the services which are considered as part of the core activity of the organization are "critical" services and must remain within the organization. Despite the above, the proposed monthly licensing model was attractive enough to SMBs (initially) will recognize the benefits of the model and will join, notwithstanding the above, to the external service. The SaaS model was also attractive for companies that offered these services since it summoned them a steady income over time and created, for them, a significant cash advantage.

"Platform as a Service"
At the positive atmosphere trend, of Win-Win relationships between service recipients and service providers, there have been further developments and in the continuation, even the development environments, which are software for everything, were separated from infrastructure environment, by moving them to outsourcing ("Platform as a Service"). This has facilitated the work of many developers, in software companies, who could enjoy a computing environment which centralizes the most advanced technologies in the field.

"Infrastructure as a Service" (IaaS)
With the development of virtualization technologies, was created a possibility of running virtual machines with complete separation of the physical hardware layer from the virtual layer, in a way which enabled different organizations a manage of their IT infrastructure in a complete separation, although they relied on a shared physical infrastructure.
This development was based on another type of service, which is known as "Infrastructure as a Service" - IaaS.
The Business, according to this model, hires on a monthly basis, computing infrastructure which include: virtual servers, storage, network services, backup and security, without having committed to huge investments on infrastructure and while saving on space, human resources, costs of maintenance and the "headache" involved in self-management of computing infrastructure.

What is cloud computing?
Cloud computing refers to a new concept, evolving today, about the nature of Internet use. According to this view, instead of buying software and install it on your local computer, you can use a saved information or application, in a remote server farm and pay, only, according to actual use. This is, actually, moving of the storage and e-mail services and, of course, the backup of the information to outsourcing.

In today's era, firms use complex computing systems in order to manage the various fields, of computing, in the organization: customer lists, inventory management, e-mail, databases, Web Hosting, accounting, data backup and more. Due to the absolute reliance on computer, the database of the company has become to be one of the most important assets hers. A Business, who relies on computer systems, must take care to back up the information, because any injury of this information, whether intentionally or as a result of human error, can cause serious damage and even disabling, in some cases.
Instead of building a computer room, in the business, it is possible to hire the services of a cloud computing services provider, who operates and maintains complex computer systems, on servers located at remote data centers, to store the company's databases, on those servers. In this way, user (a business owner, employees, etc.) can have an access to all the organization's business information, through the Internet, by a dedicated communication line.

The phrase "cloud" is used as a metaphor for the Internet and its source is in graphical flowcharts that describe the Internet in the form of a cloud. The Cloud technologies have brought a revolution, which deviated outside of the computing limits, because having a direct impact on the ability of many businesses to grow without large investments and deal with changes in demand, in dynamic market conditions. Removing barriers to entry, which were significant characteristics of the beginning of the decade, helped SMEs to penetrate the market and consequently increase competition.

"Cloud technologies" are, therefore, a general name for use in computing capabilities (software and hardware) that are not installed and maintained within the organization and that the access to them is remote, via the Internet.
Cloud computing can fit a wide range of users, from medium and large organizations till individual end users (private persons).

Cloud computing benefits: 

1. Cost savings – this is perhaps the biggest advantage. Using cloud services saves to business owner the initial investment, involved in setting up a servers' room and associated other infrastructural investments. Instead of purchasing expensive infrastructure, that requires ongoing maintenance and frequent upgrades, a business owner can make use of the infrastructure, which is constantly updated and which is managed by an external expert.

2. Flexibility – cloud infrastructure presents operating space unlimited to the user, while many services can be upgraded up or down, within a very short time, depending on actual consumption and without any long-term liabilities. Light of this important advantage of "infrastructure as a service", businesses do not need to commit in advance, according to expected growth (not always comes true according to the plan) and they enjoy high operational flexibility, depending on the actual progress, and significant savings in investments.

3. Payment according to consumption – as a derivative of the advantage of flexibility and given the fact that most cloud services can be renewed on a monthly basis, it is possible to adjust the actual consumption expenditure, a fact that has a true revolution.

4. Eliminating the dependence on physical space – cloud computing eliminates, in fact, the organization's dependence on the physical location of the servers. In reality, in which each user can access the company's databases from anywhere, an organization can save in physical space and in access time to the databases of company.

5. Technological innovation – By using cloud technologies, the organization obtains access to the latest versions of software and hardware services, which are needed for its activity.

6. Prior knowledge is not necessary – most of the technological challenges, in managing servers and advanced service software, goes to the cloud services' provider.

7. Savings in employing costs of professional staff – Since hiring professional workers, in the field, is required only when there are physical infrastructure, which require routine maintenance, large and medium enterprises can save the cost of employing permanent staff for the computer unit, in the organization.

8. Green Cloud computing – Cloud computing based usually on green technologies, which place emphasis on low consumption of energy and thereby increasing the friendship to the environment.

Disadvantages:

1. Higher dependency on cloud services - The user becomes totally dependent on cloud services and the Internet. In case of failure in the servers of the cloud services provider, or temporary shutdown of the internet line, the organization becomes to be paralyzed, because it lacks an access to one of its most important assets - the corporate information.

2. The Company's information is not possessed anymore - there is no backup to backup and therefore, at extreme cases, where the cloud provider stops working or bankrupt, the company has no more access to its databases.

3. Information Security - the centralization of the information and its availability, on the network, make it more accessible to hackers. As part of this rule, confidential or sensitive information becomes more exposed to foreign elements, despite the high security levels, which service providers are committed to implement.

4. Exposure to huge damages - damage caused in the server farm, because of a virus, or hardware failure, is usually more severe and colossal, than if only one edge unit is impaired. Repair, of such systemic damage, may take longer and cause high losses to the company.

In summary, cloud technologies brought a revolution, which its implications are far beyond the world of computing itself and which has a direct effect on the ability of many businesses to grow without large investments and deal with changes in demand, under competition in conditions of dynamic markets.