SaaS (Software as a service): is a software distribution model in which applications are hosted by a vendor or service provider and made available to customers over a network, typically the Internet. This capability eliminates the need to install software on users’ computers, and it can be helpful for mobile or transient workforces.
E-mail is a simple example for SaaS. If a user has a service provider, she requires a desktop or mobile app to access the e-mail; otherwise she can host it on individual servers. It is important to point out that the user does not manage or control the underlying cloud infrastructure, or even individual application capabilities, with the possible exception of limited user-specific application configuration settings.
Some benefits of SaaS are:
Besides the lack of control, one of the main disadvantages is that SaaS applications may not have the same features as non-SaaS applications. The functionality is often not as refined or as full. Nevertheless, this problem will diminish over time. Development tools for SaaS applications are becoming much more capable. Finally, the speed can be other disadvantage; generally SaaS applications are slower than the corresponding non SaaS equivalents.
Some examples of SaaS providers are