The expression "on-line experimentation" seems originated from the pneumatic instrumentation and control systems, which were interlinked by pipe-lines for compressed air. Pneumatic controllers could be adjusted "on-line", at their plant site, or "off-line".

The development of electronics enabled electrical wiring to replace air pipes. The previous use of pipe-lines probably had some influence at the later use of "on-line" and "off-line", when electrical wiring and cables were actually involved. The current expressions "telephone line" and “telegraph line” also promoted the use of "line", dealing with electrical wiring used for communication.

Also, the improvement of instrumentation facilitated the use of chemical sensors (e.g. pH electrodes) "on-line" for process control, instead of "off-line", at the laboratory, for periodically monitoring the process.

When microcomputers become available, they were incorporated (on-line) at control systems, what leaded to the development of sophisticated control techniques, as fuzzy and adaptive control, often previously developed and tested off-line by numerical simulation experiments.

Experiments on-line are typically required for fine tuning of controllers or to check the performance of sensors or actuators (e.g. valves). This justifies the expression "on-line experimentation".

The expressions "on-line" and "off-line", previously restricted to technical language, spread into common everyday language after the development of the bank terminal communication, internet, mobile phones, and other communication technologies.

Referring to "online experimentation" in the context of the internet, we mean experiments greatly dependent on its use as instrument to generate scientific data and knowledge, and not just to transmit information. The use of the internet to conduct enquires is analogous to the traditional use of phone lines or mail for the same purpose, being therefore hardly compatible with the concept of "on-line experimentation".

Dear Carlos, I am delighted with this fantastic contribution! we can carry on!

Online experimentation comprises remote and virtual experimentation aided by virtual reality components, augmented reality, sensorial devices and integrating live videos and other tools as interactive videos and serious games which promote user immersion in virtual environments recreating the real experience