Virtual testers – A virtual tester is a single instance of a virtual tester script running on a computer. Unlike GUI users, many virtual testers can run on a computer simultaneously.
A virtual tester emulates requests sent to a database, TUXEDO, or Web server. With virtual tester recording, this "back-end" network traffic is the only activity Robot records. Robot ignores GUI actions such as keystrokes and mouse clicks.
You include virtual testers in performance tests.
Because many virtual testers can run on a computer simultaneously, virtual testers let you add heavy user load to a client/server system. Virtual testers also help you determine scalability and measure response times.