What exactly is it?

How does it work?

What does it do for you?

How do you activate it?

Is there a better or worse time to do it? Why not immediately and get the bumps right off while your resources are low?

Also, I am now:

Production:
Lumber: 14 per hour (two woodcutters, lvl 1 each)
Clay: 14 per hour (two clay, lvl 1 each)
Iron: 11 per hour (one iron, lvl 1)
Crop: 11 per hour (three crop, one lvl 3, two lvl 1)

Main Bldg. lvl 3
Rally Point lvl 1
Barracks lvl 1

My resources are depleted now - 25/800 126/800 74/800 444/800 20/31 - so I have to wait, and that's why I'm asking about this plus stuff. Any suggestions for next builds, when I can, are welcome. Thanks.