- Untrained workers have presumably just immigrated from the countryside by way of the Capitol. They wear off-white overalls and produce one "labor unit" of work per turn if employed, and they can be sent into the army in a couple of somewhat weak positions. If there is only one of them, or any odd number, they cannot all be employed, because every building in your capital that requires any workers requires them in groups of two labor units.
- Trained workers have spent a turn in the trade school, at a cost of $100 and a piece of the all-important paper. They wear light blue overalls and produce two "labor units" of work per turn if employed, and they can be sent into the army in a wide variety of positions.
- Expert workers have spent a subsequent turn in the trade school, at a cost of $1000 and two pieces of the all-important paper. They wear deep blue overalls and produce four "labor units" of work per turn if employed. They can be retrained as specialist civilians (whence they return as ordinary expert workers if "disbanded") or given certain very important positions in the army.
In the left-hand panel of your city screen (the screen called "Give Industry Orders"), you can see the current numbers of each type of worker. If any are unemployed and not in training, the total number of idle labor units appears under an "arm" icon at the top of that panel and at bottom right of your warehouse window.
Every worker requires one unit of food per turn until sent out as a civilian or into the army. They need a balanced diet: for every four of them, the requirement is two grain, one fruit, and one meat (beef or fish). if your total is one above a multiple of four, you need an additional grain; add another and require another fruit, the next addition needs another grain, then the fourth addition needs meat. See the "Expansion" article for what happens if that requirement is not met.