Johnny McHardworker spends all day in your gold mine. In fact, he and his family before him have been spending all of their days in your gold mine ever since your very first one went into service. What has he learned? Well, it turns out he's figured out a way to run those mines more effectively. To you, that means a Rank Point, and for each one of those, a boost to your empire's production capability.

Skill ranks are available for each of tick based resources and adds a bonus of up to 32% for each of the following:
Food Production
Lumber Making
Gold Mining
Iron Mining
Oil Production
Learning
Mercantile (lowers your cost to buy and increases your yield on sales)
Exploring (Increases the amount of land and resources sites found)

For each skill rank in these, you get a bonus to your production and the higher ranks are worth more of a bonus than lower ranks.

There are also skill ranks for:
Attack (not yet available)
Defense (not yet available)
Training (not yet available)
Power (not yet available)

For the most part, you earn a rank point by using the associated skill. The more heavily you use that skill, the faster it will go up. Keep in mind, also, that each rank point is harder to earn than the one before it.

At any time you can instantly buy a skill rank increase with knowledge. Skills start out at a price of 1,000 knowledge points and increase by 1,000 points all the way to 20,000 to obtain Skill Level 20