The Streamlined Sales Tax Project is basically a way that grown-up people in different states decided to make it easier for stores and online shops to charge the right amount of tax when you buy something.
When you go to a store or buy something online, you usually have to pay a little bit extra money for taxes. But the thing is, different states can have different tax laws, which can make it really complicated for stores and online shops to know how much tax to charge you. That's where the Streamlined Sales Tax Project comes in.
It's like they got together and agreed on some basic rules for how to calculate taxes, so that it's simpler for everyone involved. For example, they decided that certain items like groceries or clothes might not be taxed at all, while other things like electronics might have a higher tax rate. They also made sure that shops don't have to deal with things like different tax rates for different cities within the same state.
Basically, they made a set of rules that everyone can use to figure out how much tax to charge you when you buy something, no matter where you are in the country. So when you go to the store or buy something online, you can trust that the tax you're being charged is fair and follows the same rules that everyone else is using.