It is my job to make things like this. There are also many other jobs that help other people like me.
Wait a second, didn't you just have something different? How did you get that strawberry ice cream?
SIX HOURS LATER
Oh yeah, I forgot to tell you that you can trade for what you make at your job for other things that you need more. I really needed ice cream because I didn't have any food so I traded what I make for my job with someone who needed what I made.
Wait a second, first you have a pot to put things in, then you get strawberry ice cream, now you have Starbucks! I need to know more about this, what other things can you trade for, and do you know if I can trade my clothes for some Pete's Coffee?
THE NEXT DAY
Oh yeah, I don't know why I am keep on forgetting to tell you things, but since I traded my pot to put things in for two ice cream, I only ate one so I traded the other one for some Starbucks Coffee. There are other things that you can trade for like animal skins and other useful resources
People get assigned jobs for the city such as potters, craftsmen, traders, tax collectors and many more. And they all have different roles.
You can trade for what you make on your job for others things that you need more then what you make on your job.
The most common things that they traded were animals, plants, and other resources they found nearby. When people started settling in villages and towns, people started trading more often and trade was more useful. (You couldn't trade for Starbucks Coffee and Pete's Coffee back then. It is just for a little joke. :)