Yesterday, President Donald Trump announced a slew of tariffs on nearly every country in the worldover 180 of them, notes CNBC. The tariffs Trump announced are higher than most economists and business leaders feared.Trump chose to hold off on announcing the tariffs until after the markets closed yesterday, and after seeing how those markets have since reacted, its easy to understand why. Individual stocks and the markets as a whole plummeted after the tariffs were revealed, and in premarket trading, those markets and stocks remain greatly depressed.Major American companies like Apple, Amazon, Nike, Tesla, and Walmart are seeing their share prices decline this morning, while Nasdaq, Dow, and S&P futures have fallen significantly.President Trumps tariffs explainedTrumps tariffs were announced yesterday on a day the president coined Liberation Day. Business leaders, economists, and global heads of state were on edge before the announcements, fearing just how high the tariffs would be.It turns out, in many cases, they were worse than expected.President Trump announced a minimum 10% tariff on nearly every country worldwide. That means that nearly every good that is imported into the United States will be slapped with a default 10% levya levy which will then either have to be absorbed by the U.S. company importing the product, leading to reduced profits, or passed on to American consumers, leading to increased prices.However, countries that were only hit with a 10% tariff could count themselves relatively lucky. Thats because Trump levied much higher tariffs against dozens of countries, which are also the countries from which American companies import most of their goods and parts.Here are some of the countries that got hit the hardest with high tariff rates:China: 54%Cambodia: 49%Vietnam: 46%Bangladesh: 37%Thailand: 36%Taiwan: 32%South Africa: 30%India: 26%Japan: 24%European Union (27 member states): 20%There are two big omissions from the list of key trading partners above: Canada and Mexico. Trump did not announce new tariffs on either country yesterday, but previous tariffs imposed on both nations remain in place, notes Reuters.Reactions from global leaders to the swatch of new tariffs have been vocal and swift. Many condemned Trumps tariffs and vowed to retaliate in kind, leading to fears that an all-out global tariff war is about to begin. Foreign stock markets have already fallen today, but the worst fall may be yet to come when U.S. markets open in just a few hours.American stock marketsand tech sharessinkAmerican investors are already not taking the news of Trumps tariffs well. As of the time of this writing, Americas three largest stock markets are down a significant amount, according to data from Yahoo Finance:S&P 500 Futures: down 3.23%Dow Futures: down 2.57%Nasdaq Futures: down 3.6%But things are even worse for many big-name tech stocks. Here is how many of Americas largest tech giants shares have reacted as of the time of this writing:Alphabet Inc.(Nasdaq: GOOG): down 2.76%Amazon.com, Inc.(Nasdaq: AMZN): down 5.7%Apple Inc.(Nasdaq: AAPL): down 7.4%Meta Platforms, Inc.(Nasdaq: META): down 4.23%Microsoft Corporation(Nasdaq: MSFT): down 2.27%NVIDIA Corporation(Nasdaq: NVDA): down 4.46%Shopify Inc. (Nasdaq: SHOP): down 10.13%Taiwan Semiconductor Manufacturing Company Limited(NYSE: TSM): down 4.84%Tesla, Inc.(Nasdaq: TSLA): down 4.86%As you can see, some tech stocks are being hit worse than others. Apples shares are among the worst hit. A significant reason for that is that Apple manufactures most of its products in China, Vietnam, and Indiaall countries that got hit with some of the most considerable tariffs. That means that Apple will either need to absorb those costs or increase prices for consumers.If Apple does the former, it will reduce the companys margins and profitability. If it does the latter, fewer people may buy its products, reducing the companys profitability.Likewise, NVIDIA and TSMC shares are among the biggest tech losers since their products rely on supplies from some of the hardest-hit countries, including China and Taiwan. As for Amazon, many of the goods the company sellsfrom tech to clothingcome from a number of the hardest-hit countries, including China, Vietnam, Bangladesh, and more.Shopify is one of the hardest hit tech companies this morning, because many of the goods sellers on its platform offers originate from the countries that are hardest hit by Trumps tariffs.As for Tesla, many of the components that go into its electric vehicles are sourced from overseas. Even tech giants that dont generate too much of their revenue from selling physical goods imported from overseaslike Meta and Googleare seeing their share prices fall, because those companies rely on infrastructure made overseas, like servers, to keep their businesses going.Physical retailers and apparel makers see stock prices get hit, tooBut its not just Americas tech stocks that are getting hammered. Here is how many of Americas largest retailers and apparel makers shares are reacting:Costco Wholesale Corporation(Nasdaq: COST): down 3.4%Lululemon Athletica Inc.(LULU): down 12.48%NIKE, Inc.(NYSE: NKE): down 9.6%Target Corporation(TGT): down 5.12%Walmart Inc.(NYSE: WMT): down 4.96%Much of the apparel Americans buy comes from countries like China, Bangladesh, Vietnam, and Indiaall of which were hit hard by Trumps tariffs. Its no wonder then that apparel makers, including Lululemon and Nike, are seeing some of the biggest share price drops today.And just as Amazon and Shopify are seeing large declines in their stock prices, Americas brick-and-mortar retailers are as wellagain, due to the fact that they import many of their goods from the countries hit hardest by Trumps tariffs. These retailers include Costco, Target, and Walmart.How will the tariffs affect me?Every American will likely be affected by Trumps tariffs. This will primarily happen in two ways.First, Americans will likely see most of the goods they buyfrom gadgets to food to clothing to carsjump in price over the next days and weeks. This means Americans money will be able to buy less, and Americans with lower incomes will be hit harder than those with higher incomes because they already have less discretionary spending power.Second, as of this morning, many Americans who invest directly or indirectly in the stock marketwhether through a brokerage account, 401 (k), or pension planwill likely see their investments be hit. Those who dont need to tap into these funds for years or decades may be able to ride out the tariff storm. But those older Americans who are or will be tapping into their investments in the coming weeks will, if the stock price declines today hold, see that their investments are worth less than they were before the tariffs went into effect.However, as poorly as the markets have already reacted after Trumps tariff announcements yesterday, things could get even worse in the days ahead. Thats because we do not yet know how, exactly, other countries will respond. If they respond as strongly in kindand its likely many will, including trading powerhouse Chinathen many experts fear that Trumps tariff wars could lead to another global recession like the one the world has not seen since 2008.