Any program or code that runs on a computer is an example of software, and anything you do with a computer requires the use of software.

What is a Software? A software or computer software essentially a type of programs which enable the users to perform some particular specific task or actually used to operate their computer.

What is Software as a Service (SaaS). This post talks of advantages and gives examples of companies like Mozy, Prey, OneDrive Sync, Office Web Apps, etc.

SaaS or software as a service uses cloud computing to provide users with access to programs via the Internet. It commonly uses a subscription service format.