Virtual Work is the principle formulated by Johann Bernoulli stating:
"If an elastic structure is in equilibrium under a given system of loads and temperature distribution, then for any virtual displacement away from a compatible state of deformation the virtual work is equal to the virtual strain energy."
This is heavy stuff...
We prefer to think of VirtualWork this way:
"When you use IES tools it appears that you are working,
when in fact, you are playing: creating and executing
wonderful designs, resulting in the appearance of actual work."