Virtual laboratories are extremely popular on the web. It might be said that the whole idea originated from the need to remotely control experiments within CERN. Just like the computer governing of experiment is a normal and often the only way to manage experiments, the governing of experiments over the web is the natural step forward.
Along with the beginning of Windows, a trend of computer simulations of different instruments in measuring appeared. Program versions of measuring instruments appeared on the computer screens. Out of these versions, whole laboratories were formed.
In those laboratories students can conduct computer experiments and simulations, e.g. in biology, physics and mathematics. With certain types of experiments that are conducted through the computer in real life, students hardly notice the difference compared to real experimental work.
It is more and more common to find original experimental data available on the web. As if the real laboratories are becoming more and more like the virtual ones.
These are all arguments in favour of virtual laboratories. It shouldn't be forgotten, however, that real physical contact with the experiment is sometimes necessary in order to understand its true nature.