system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What are trade tariffs and what effect do they have on a nation’s economy?
gpt
A tariff is a trade tax on goods, basically. Usually it’s done by countries who are allowing imports of certain goods.

Imagine the US has a bunch of cookies that we made here to sell to our own population. They’re great cookies. They’re $1 each.

Now China comes along and says “hey, we got some cookies we want to sell to the US people also.” But China’s cookies are only 10 cents each, and they’re pretty much equal in quality to the US cookies.

What this means is that suddenly a lot of money is going to be flowing from the US to China, since nobody’s going to want to pay the higher price for domestic goods. So the US government steps in and says “actually… we’re gonna put a tariff on those Chinese cookies. Let’s say… we’ll tax them at 90 cents each.” Suddenly, all cookies for sale in the US are back to costing about $1 — so people will theoretically buy US cookies at the same rate or more than the Chinese cookies. And maybe China won’t even bother wanting to sell cookies here anymore, because it’s too expensive for them to do so.

NOTE: The above explanation is a SUPER simple version of one type of tariff; they can get quite complicated and have a lot of legal complexities. But this should kind of give you the basic gist of why they’re a thing.