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Today, financial types are very worked up over the yield of a 10-year note from the U.S. Treasury, which has officially crossed the threshold of 3%. For most of us, a decade from now, our biggest asset will still be our student loan debt, so who cares, right? You should. Everyone should, in fact. Because the ten-year Treasury bond is essentially what it costs to buy money. And if it goes up, your credit cards may cost more while your paycheck buys less, even as stores close and jobs are lost. Here’s what you need to know, and why it’s important.

The 10-year U.S. Treasury note is seen by people who think about money as the safest possible investment: If you’ve ever wondered how the U.S. can have a “national debt” and still be open, the short answer is Treasury notes and bonds, which are sold at all sorts of terms at all sorts of rates. Here’s how it works. Let’s say a note has a face value of $1000. You buy the note for a price below that face value, say, $950, and at a certain percentage rate, 3% in this case, which pays out twice a year. So, for your $1000, you get $30 a year for ten years, and then you get paid the full value of the bond, $1000. So for your $950 you’ve made $1300. Technically there is some risk to this, but investors love U.S. Treasury notes because the United States makes its payments. So, they pay well and they are about as safe as investing money gets. Plus if you want to invest your money elsewhere, you can just sell them to somebody else.

Treasury notes also predict inflation, so higher yields are bad news for your paycheck: Remember, we’re talking about a decade here. Treasury notes have to beat inflation, as a result; that is, if you spend that $950 in 2006, from our example above, it needs to have a return better than inflation, which in this case would be $1135 in 2016. If the yield is going up, that means a lot of people are convinced inflation is going to rise faster than it has in past, which means your actual paycheck is not going to go as far.

Thanks to these two factors, Treasury notes help set the cost of literally everything else involving money: Remember, in investing, the higher the risk of losing your money, the more the investment has to pay out. So even if you have the second safest possible investment, it still needs to offer a higher rate of return than a Treasury note. Thus rising rates put pressure on the interest rates of everything else, potentially pushing them beyond the point where they’re sensible investments. It’s a rock thrown in the pond; as the rate ripples outward, particularly in investments that range across ten years or so, you start seeing the effects. It’s not the only rate that matters, but it’s a key one.

The relatively good news, at the moment, is that this is happening there are a lot of notes hitting the market: Remember the GOP’s big honking tax cut? Yeah, this is how it gets paid for. Simple economics are at play here; when there’s an excess of supply, and investors are expecting the Treasury to set a record in sales, you have to sweeten the pot to get people to buy.

But that has its own set of problems in the short term: Why? Well, let’s say you’ve got $1000 to divvy up between stocks and bonds. You want the highest rate of return with the least risk, right? And if that’s bonds, which remember are as close as you’re going to get to guaranteed money, why the heck would you buy a single share of stock? This is why when bond rates rose in February, the stock market took a hit: Investors were afraid everybody was going to ditch stocks for bonds. If enough people are convinced bonds are a better deal than stocks (and consider the president is out there trying to start trade wars) there could be another correction or a full-on stock market crash, depending on how apocalyptic you want to get: Bond yields shot up right when the Great Recession really took hold.

It’s also bad news for companies in debt: Most companies raise money, either to pay off debt or expand, by selling bonds themselves. For companies in debt, selling those bonds at the lowest price possible becomes incredibly important, and rising Treasury note rates make that harder. Not being able to sell bonds is part of what sunk Toys R’ Us, for example. And there are a lot of so-called “zombies,” companies that are making just enough money to pay the interest on their debt, but not the principal. A rise in interest rates might kill a lot of them all at once.

And then there’s the long-term problem: Keep in mind, this is setting the price of buying and selling things for a decade. Anything with an interest rate is going to be affected by this, even if it’s indirect. Buying a car, refinancing a student loan, even using a credit card could potentially cost more depending on how this all shakes out over time.

In other words, even if you’ll never buy a Treasury note in your life, the rate affects you and will affect you for a long, long time.