The Boston Tea Party
The anger was directed at the government of Great Britain, which at that time had passed the Tea Act, a law that almost guaranteed that the American colonists would buy tea from the East India Company. Why? Because the law lowered the price on tea that the East India Company so much that it was the cheapest tea around. In fact, it was way below the price charged by other tea companies. Most American colonists, looking for ways to cut costs and save money, would choose a cheaper tea over a more expensive tea any day.
Why did this law come about? Well, the East India Company wasn't doing so well and the British government wanted to help the company get back on its feet.
Other tea companies weren't happy about the Tea Act, of course, but the American colonists viewed it as another example of "taxation without representation": In effect, the Tea Act was putting a tax on tea sold by companies other than the East India Company. As with the Stamp Act and other unpopular taxes, they were all voted in by Parliament, which was thousands of miles away, and the American colonists had no way to influence the law or speak out against it while it was being debated in government.
So the colonists were angry. They wanted to do something else to let the British know about the unhappiness that the Tea Act was causing. Some people wanted to keep things nonviolent; others wanted bloodshed. The result was somewhere in the middle.
Christmas was approaching in the year 1773, and the colonists faced another year of unopposed and unrepresentative taxes. The Sons of Liberty decided to take action.
Donning disguises that made them look like they were Native Americans, a large group of the Sons of Liberty on December 16 stormed aboard those three unsuspecting British ships and dumped 342 crates full of tea overboard. By any standards, that's a lot of tea. These crates happened to be jammed full of tea, and so the companies that made that tea lost a lot of money that night.
Because the Sons of Liberty were disguised as Native Americans, they could claim that they were not guilty of dumping the tea. The British government knew better, of course, and grew angrier than ever at what it saw as Americans' ingratitude. The very next year saw the passage of what came to be called the Intolerable Acts, one of which closed the port of Boston entirely.
The Boston Tea Party was a symbolic act, an example of how far Americans were willing to speak out for their freedom. Two short years later, Americans were willing to give their lives for their freedom, as shots rang out on Lexington Green.