One of the most popular forms of cloud computing is software-as-a-service, SaaS(/sæs/) for short.

It is is software licensing and delivery model in which a service provider hosts applications for customers and makes them available via the internet. That is app software, and app data etc are located in the service provider’s data center.

One common example is email.

SaaS is one of the three major categories of cloud services, along with IaaS(infrastructure-as-a-service) and PaaS(platform-as-a-service).

Advantages

1. pay-as-you-go
2. Access app from anyåwhere or any device
3. Predictable ongoing costs
4. No worry others.The service provider manages the hardware and software, and with the appropriate service agreement, will ensure the availability and the security of the app and your data as well.

Risks

1. Customers need to rely on 3rd instead of themself, such as security and privacy issues
2. Lose some level of control which is one of the trade-offs of cloud computing in general
3. New version. Maybe not want adopt the cost of new version.
4. Migrate to a new SaaS provider is not easy