A software robot is an AI (artificial intelligence) system that runs on a host device rather than existing as a standalone machine.
Examples of software robots include expert systems, virtual assistants and other chatbots. In fact, any type of software that incorporates AI might be called a software robot, especially those that feature machine learning and those that automate formerly manual processes. That means that a great many commonplace applications, including spam filters and antivirus software, could be considered software robots.
By definition, a robot is a physical system with the capacity to move independently and which, depending on its purpose, may or may not include AI software. The term software robot arose to differentiate software-based systems from physical ones. That distinction has become increasingly unclear as more and more applications are referred to as robots, especially in the press.
When articles about the AI attorney called the expert system a robot lawyer, for example, some readers imagined a humanoid robot (android) practicing law, wheeling about the courtroom. In fact, the so-called robo-lawyer is a software application that combines AI with a legal system knowledge base; similar systems exist in the financial and healthcare sectors.