What is "Light" when we're sending it??

Consider the how much on this site is connected to "Light". Even the name itself "Light Workers". What does the symbol 'Light' represent to you (definition)? What beliefs are attached to it? What has your experience taught you of "Light"? Is it real? If so, explain, please.
I am off to work for now. Will be interesting to see responses when I return.

Comfort the disturbed, disturb the comfortable.
Mark